The United States extended a short olive branch to Iran Wednesday, offering to join European leaders in their talks with Iran over its nuclear program — provided Tehran stops enriching uranium. But Iran quickly swatted the olive branch away, dismissing Secretary of State Condoleezza Rice's remarks as "a propaganda move."

"To underscore our commitment to a diplomatic solution and to enhance prospects for success, as soon as Iran fully and verifiably suspends its enrichment and reprocessing activities, the United States will come to the table," Rice said at the State Department.

Shortly after, the official Iranian news agency IRNA offered its response:

"It's evident that the Islamic Republic of Iran only accepts proposals and conditions that meet the interests of the nation and the country. Halting enrichment definitely doesn't meet such interests," the agency reported.

"Given the insistence by Iranian authorities on continuing uranium enrichment, Rice's comments can be considered a propaganda move."

But John Bolton, U.S. Ambassador to the United Nations, said the U.S. would not bend on its offer.

"I think Secretary Rice was very clear on this today that this is a precondition on which we're not going to compromise," Bolton said in an interview on FOX News.

"They have to suspend their uranium enrichment and plutonium reprocessing activities. If they do that, that's a sign they're willing to have serious discussions. ... If they're not willing to do that, the other alternative is clear also: We will move for economic and political sanctions."

Earlier in the day, top U.S. officials expressed hope that the moves would yield progress, but stood firm against allowing Iran to take a path toward nuclear weapons.

At the White House, President Bush said, "I believe that it's important that we solve this issue diplomatically, and my decision today says that the United States is going to take a leadership position in solving this issue."

Rice said the United States and its European partners, Britain, France and Germany, known as the EU-3, have put together a package that offers both carrots and sticks, or benefits and penalties, for Iran if it does not comply with international demands that it end its nuclear weapons pursuit.

"The Iranian regime can decide on one of two paths, one of two fundamentally different futures for its people and for its relationship to the international community. ... The negative choice is for the regime to maintain its current course, pursuing nuclear weapons in defiance of the international community and its international obligations. If the regime does so, it will incur only great costs," including international isolation and progressively stronger political and economic sanctions, she said.

"The positive and constructive choice is for the Iranian regime to alter its present course and cooperate in resolving the nuclear issue, beginning by immediately resuming suspension of all enrichment-related and reprocessing activities as well as full cooperation with the IAEA ... This path would lead to the real benefit and longer-term security of the Iranian people, the region and the world as a whole," Rice added.

Rice said if Iran cooperates, the benefits could be extended beyond civil nuclear energy and could include progressively greater economic cooperation.

White House spokesman Tony Snow said Rice's speech does not mark a change in Washington's position, he said.

"There are not going to be direct one-on-one talks with Iran. That's not part of the deal," Snow said.

But the decision to change tactics toward Iran is a major policy shift for the Bush administration, which has refused to join the talks or make other diplomatic overtures to Iran, despite calls from European nations, other leading diplomats and former U.S. secretaries of state.

Still, International Atomic Energy Agency Director General Mohamed ElBaradei welcomed the announcement by Rice to join the talks to get Iran back to the IAEA Board of Governor's call for the suspension of enrichment-related and reprocessing activities.

"Dr. ElBaradei strongly encourages Iran to create the conditions necessary for the resumption of these talks, with U.S. participation, with a view to achieving a comprehensive settlement that is acceptable to both the international community and Iran," reads a statement released from his office in Vienna, Austria.

In a series of phone calls Tuesday, President Bush spoke with Presidents Vladimir Putin of Russia and Jacques Chirac of France and Chancellor Angela Merkel of Germany about Iran, Snow said.

The leaders signed off on the details regarding an incentive package. Snow said their overall position is that Iran must take the first step by suspending enrichment and reprocessing activities, which are still the foundation for U.S. diplomatic policy on the matter.

The United States and the European nations that led stalled talks with Iran last year have agreed on the basics of the package for Iran if it is willing to give up its disputed activities, Rice said. In response to a reporter's question, Rice said the partners have made substantial progress on the package, first negotiated in New York a few weeks ago, but a few outstanding issues are going to be worked on in Vienna, Austria, where diplomats were meeting on Wednesday.

Despite those outstanding pieces, the international community is in agreement, she said.

But diplomats in Vienna added another condition Wednesday, saying that Washington would consent to talks only if Russia and China agreed to back U.N. Security Council sanctions against Iran if it remains defiant on the enrichment issue. China and Russia have both said they oppose the use of sanctions against Iran.

Rice, who is on her way to Vienna for a meeting with U.N. Security Council members, sidestepped a question on that issue, alluding only to substantial agreement reached in New York that U.S. participation in talks removes one of the last excuses for Iran not to cooperate.

"There is a strong international consensus that Iran must not have a nuclear weapon, that Iran must adhere to the international community's demands that it suspend enrichment — we have complete and total agreement on that," she said.

"We hope that in the coming days the Iranian government will thoroughly consider this proposal."

Iran has so far refused to do what the United States is demanding as a first step to talks. Iran did voluntarily suspend uranium enrichment activities while talks were active with the Europeans last year but resumed and stepped up those activities this spring.

Rice noted that President Bush wants the United States to have a positive relationship with Iran, particularly with its people, through increased contacts in education and cultural exchanges in sports, travel, trade and investment.

Besides the nuclear issue, to get to a positive relationship Tehran must also stop supporting terror, including in Iraq, and stop undercutting the restoration of full sovereignty in Lebanon.

"These policies are out of step with the international community and are barriers to a positive relationship between the Iranian people and the people of the United States, as well as with the rest of the world," she said.

She also warned that Iran should not underestimate the United States' position on its nuclear weapons hunt or threats to its allies.

"If the Iranian regime believes that it will benefit from the possession of nuclear weapons, it is mistaken. The United States will be steadfast in defense of our forces and steadfast in defense of our friends and allies who wish to work together for common security," she said.

The Swiss ambassador to the United States was delivering Rice's remarks to the Iranians, and the Iranian ambassador to the United Nations also received a copy. The United States has had no official direct talks with the Iranians since the two countries cut diplomatic ties following the occupation of the U.S. Embassy in Tehran by radicals in 1979.

However, the U.S. ambassador at the United Nations had a "courteous conversation" Wednesday with his Iranian counterpart to tell him about Rice's proposal, said Richard Grenell, a spokesman for John Bolton.

It was a rare one-on-one discussion between Bolton and Javad Zarif. Bolton has said previously there are a few diplomats at the U.N. he never talks to — from Iran, North Korea, Venezuela and Cuba.

FOX News' Maya Zumwalt and The Associated Press contributed to this report.