The Bush administration said Tuesday that any enrichment of nuclear fuel on Iranian territory was unacceptable, while Vice President Dick Cheney said the United States won't tolerate Tehran possessing a nuclear weapon.

"The Iranian regime needs to know that if it stays on its present course, the international community is prepared to impose meaningful consequences," Cheney said in a speech to the American Israel Public Affairs Committee. "We join other nations in sending that regime a clear message: we will not allow Iran to have a nuclear weapon."

Cheney also echoed remarks made to the same conference over the weekend by John Bolton, America's ambassador to the United Nations, when he said Iran's insistence on enriching uranium will lead to "tangible and painful consequences."

White House officials say they fully expect the matter to be taken up by the U.N. Security Council this week. The Bush administration spearheaded the effort to get the International Atomic Energy Agency to refer the Iranian nuclear issue to the Security Council, which it did.

"We will see what is necessary to do in the Security Council," Secretary of State Condoleezza Rice said Tuesday after meeting with Russian Foreign Minister Sergey Lavrov. She said there was still time for Iran to change its ways.

Russia appears to be closing ranks with the United States over Tehran's nuclear program. Moscow had offered to allow Iran to enrich uranium on Russian soil for energy needs in order to take some heat off the Islamic Republic from the international community so it can avoid sanctions.

But some media reports had suggested Lavrov's mediation efforts on the nuclear issue have driven a wedge between Washington and Moscow since he reportedly was considering allowing Iran to enrich a small amount of uranium domestically. At a joint State Department news conference, Lavrov and Rice said there was no such compromise in sight with Iran.

"The Russians did not tell us of any new proposal that they have made to the Iranians," Rice said during the press conference. "We still hope that this can be resolved in a, through negotiations, through the IAEA. But it's going to require the Iranians to suspend their activities."

"There is no compromise, new Russian proposal," Lavrov said, insisting that his government's negotiations with Iran are bound by a Feb. 4 initiative, endorsed by the IAEA, that would provide for uranium enrichment to be conducted only in Russia for Iran's fuel needs. "(W)e repeatedly stated that it's only in this context that this joint venture initiative is available," he emphasized.

But Iran's envoy to the IAEA said Tuesday that his country was not prepared to freeze small-scale enrichment, a key demand of not only Moscow and Washington, but of the European Union and many other nations, as well.

"We've spent a lot on this," said the envoy, Ali Asghar Soltanieh, outside a 35-nation IAEA board meeting that is preparing to focus on Iran.

That IAEA meeting in Vienna ended Tuesday with no discussion of Iran, however; the issue is expected to be brought up during Wednesday morning's meeting.

Rice and Lavrov later met with President Bush at the White House for about half an hour. Asked afterward if Russia would accept sanctions against Iran, which Moscow has seemed reluctant to do, Lavrov said, "Have you seen a proposal for any sanctions? This is a hypothetical question, yes?"

Earlier in the day, White House spokesman Scott McClellan said the U.S. expects the U.N. Security Council to move forward to rebuke Tehran for its disputed nuclear program.

"The international community has spelled out what Iran must do — that means suspend all enrichment activity," McClellan said.

McClellan's comments came as a diplomat at the IAEA meeting told The Associated Press that Iran is offering to suspend full-scale uranium enrichment for up to two years. The offer reflected Tehran's attempts to escape Security Council action over the activity, which can be used to make nuclear arms.

The diplomat said Tehran's offer was made Friday by chief Iranian negotiator Ali Larijani in Moscow in the context of contacts between Iran and Russia on moving Tehran's enrichment program to Russia.

McClellan said Iran "has shown it cannot be trusted.

"It hid its nuclear activities for two decades from the international community. It has refused to comply with its international obligations. This is about the regime and its behavior. That's what this is about and that's what our focus is," he said.

Russia is also a key player in the U.S. drive to limit aid to the extremist group Hamas, which has taken control of the Palestinian legislature.

The U.S. desire for Russian help against Hamas is just one of several cards Lavrov holds as the Security Council prepares to take up the case of Iran's disputed nuclear program.

Russia, which has veto power as one of the permanent members of the Security Council, is perhaps Tehran's most important ally and business partner.

China, which also has veto power on the Security Council, is appealing for further negotiation. "Iran should cooperate closely with the IAEA to settle the nuclear dispute," Foreign Minister Li Zhaoxing said Tuesday in Beijing at a news conference. "There is still room for settlement of the issue in the IAEA."

The United States won a diplomatic coup in February when Russia went along with the U.S.-backed effort to report Iran to the council, but had to agree to a delay of at least a month before the council could take any action. That window is closing without the progress Russia hoped to claim on its proposed nuclear compromise.

FOX News' Teri Schultz and The Associated Press contributed to this report.