“I suppose the Iranians can threaten but they are deepening their own isolation,” Rice said during a visit to Athens.
Iran’s chief nuclear negotiator Ali Larijani said on Tuesday his country would suspend its relations with the International Atomic Energy Agency (IAEA) if sanctions were imposed.
The United States accuses Iran of wanting to build nuclear bombs and has been seeking support for international sanctions if Tehran does not halt uranium enrichment, as demanded by the U.N. Security Council. Russia and China oppose such measures.
Tehran says its nuclear programme is aimed at generating electricity.
Washington has refused to rule out military options if diplomacy fails to curb Iran’s atomic ambitions.
Rice told a news conference in the Greek capital, a stop in a trip that also includes Turkey and Bulgaria, that the international community needed to take “credible” steps to prevent Iran from continuing to develop its nuclear programme.
The IAEA reports to the Security Council on Friday on whether Teheran has complied with their demands.
Rice said the United Nations will consider measures to be taken next but those cannot be just statements “in light of Iran’s continued defiance of international norms”.
“I think that we are going to have to take a next step. It seems logical that we should consider a Chapter 7 resolution under the Security Council’s mandate,” she said, referring to a resolution that allows for sanctions or even military action.
