The United States rejects Iran's offer to allow a watchdog agency to inspect the country's nuclear facilities and will press ahead for U.N. penalties against Tehran, Secretary of State Condoleezza Rice said Sunday.

"They've had plenty of time to cooperate. I think they're playing games," Rice said.

Iran on Saturday offered to allow inspections to resume if the Security Council turned over the dispute to the U.N. nuclear monitor, the International Atomic Energy Agency.

A report from the IAEA confirmed that Iran had successfully produced enriched uranium and defied the Security Council's Friday deadline to stop the process.

Rice said the offer to resume IAEA inspections suggests the Iranians "are indeed somewhat concerned" about actions the Security Council might take to further isolate Iran.

Her remarks contrasted with comments from her predecessor at the State Department, Colin Powell, who said in an interview broadcast Sunday in London that Iran seems to "have pretty much decided they can accept whatever sanctions are coming their way."

Regardless, Rice said the U.S. probably would seek a U.N. resolution that would require Iran to comply with demands that it stop enriching uranium. Rice mentioned a resolution under Chapter 7 of the U.N. Charter, which means it can be enforced through penalties or military action.

"The international community's credibility is at stake here," she told ABC's "This Week."

"And we have a choice, too. We can either mean what we say, when we say that Iran must comply, or we can continue to allow Iran to defy."

While the U.S. and its European allies are pushing for possible penalties, Russia and China — veto-wielding Security Council members — have opposed the idea.

Iran insists it has no plans to make nuclear weapons and does not need or want them. The United States, Britain and France suspect the program is aimed at producing nuclear warheads.