Updated

A package of incentives and disincentives to get Iran to stop enriching uranium has not been rejected at first sight, a reaction that President Bush said Tuesday "sounds like a positive step."

"We will see if the Iranians take our offer seriously," Bush said in an impromptu conference with reporters in Laredo, Texas, where he was visiting U.S. Border Patrol area headquarters.

"I have said the United States will come and sit down at the table with them so long as they are willing to suspend their enrichment in a verifiable way," Bush said. "So it sounds like a positive response to me.

"I want to solve this issue with Iran diplomatically," he added.

In a marked change of tone, Iranian officials did not immediately dismiss the West's latest proposal for ending the nuclear standoff. Personally conveyed by Javier Solana, foreign policy chief of the European Union, the offer emphasizes the positive, a senior Bush administration official told FOX News.

In his presentation of the package, Solana briefed Iranian officials extensively on Tuesday about the incentives involved but "went into a lot less detail" on the disincentives, the official said.

"There are robust measures on both sides, both the incentive side as well as the disincentive side," State Department spokesman Sean McCormack told reporters in his daily briefing. "It presents the Iranian government with a very clear choice on both sides of the road."

The Bush administration official who spoke to FOX News on condition of anonymity said it was possible Solana transmitted paperwork to the Iranians outlining the incentives, but certainly did not transmit any paperwork on the disincentives. The decision to convey less information about the disincentives to the Iranians was agreed upon in advance by the six powers, made up of the U.N. Security Council's permanent members — the U.S., U.K., France, Russia and China — plus Germany, who crafted the package.

If no deal is reached, the Security Council could move to sanctions such as travel and financial restrictions on Iranian officials.

The package is said to include a promise of a waiver of U.S. legal restrictions to allow export of some agricultural technology and U.S. and European backing for Iran to join the World Trade Organization, diplomats and others said.

Other sources have said that the offer also provides access to American nuclear technology, help in building light-water reactors and long-sought aircraft and spare parts from Boeing and Airbus.

Asked about the technical help offered in the package, McCormack urged reporters to take the leaks, which appeared to have come from European diplomats in Vienna, with a "grain of salt."

"U.S. security guarantees, U.S.-based security guarantees, U.S. participation in security guarantees ... not on the table," he said, adding that the negotiations are not taking place in Vienna, though that's where the deal was struck for the package contents among the six powers involved.

The senior administration official would not confirm or deny any elements in the package to FOX News, but when asked about that specific alleged elements, said a report containing the technology incentives "was a little overwritten."

Receiving the briefing in Tehran was the country's top nuclear negotiator Ali Larijani, who was "welcoming" of Solana's visit and promised to look "seriously" at the package presented, but said "ambiguities" in it need to be removed.

Larijani also falsely portrayed the diplomatic initiative as one in which the United States is not involved.

"We recognize Europe's decision for solving Iran's nuclear issue through negotiations as a positive step," he said.

After his meeting, Solana returned to Brussels, from where he called Secretary of State Condoleezza Rice to discuss the details of his visit.

Recounting the discussion, McCormack said Solana called the meeting "very useful and constructive," but said the Iranians told him that they would consider the proposal but need time to review it. Solana said that he would be in contact with the Iranians in the coming days about the proposal, according to McCormack.

He added that the United States will give Iran "a little bit of space" to consider the package, but repeated that the offer is not open-ended.

"It's a matter of weeks, not months," he said.

"We want to give this every opportunity to succeed," McCormack added. "The diplomacy, I would say, is at a sensitive stage ... We want to give them a little bit of space to consider what's in the package, both on the positive as well as the negative side."

The Bush administration would not say exactly how long it will refrain from discussing specifics of the package, but White House press secretary Tony Snow put the onus on Iran.

"If the Iranians agree to suspend enrichment-related and reprocessing activities, then we'll be able to discuss more openly what the incentives are, and we certainly hope that that's the case," Snow said.

Despite the renewed negotiations, a policy decision pushed by Rice about six weeks ago, the Bush administration still considers Iran a state sponsor of terrorism and its leaders grossly anti-Semitic.

Still, Rice determined that only direct U.S. involvement could restart stalled negotiations with the Iranians, and last week, the United States offered to bargain directly with the Iranians if they first put disputed nuclear development on hold.

FOX News' James Rosen and The Associated Press contributed to this report.