Germany said on Wednesday Iran could not be allowed to harm the United Nations by pursuing its nuclear programme, but Russia said using force against Iran must be ruled out and also questioned the need for sanctions.
In Vienna, crucial EU-Iranian talks meant to explore ways of avoiding resort to UN sanctions were postponed on Wednesday but could be held on Friday, Tehran's ambassador to the International Atomic Energy Agency (IAEA) told Reuters.
US Secretary of State Condoleezza Rice told IAEA chief Mohammed ElBaradei by telephone that Washington still preferred diplomatic progress over the use of sanctions, "but within weeks, not months," a senior diplomat said.
German Chancellor Angela Merkel's comments were among the strongest from a European leader since Iran ignored an August 31 UN deadline to stop enriching uranium.
"Iran's response is not satisfactory. We won't close the door to negotiations but we the international community won't stand by and watch as Iran harms the rules of the UN nuclear authorities," Merkel told German lawmakers in a speech.
She made clear that military action against Iran was "not an option." Washington has not ruled this out as a last-resort alternative should negotiations or sanctions fail to sway Iran.
But sanctions are an option, German diplomats say, and will be discussed at a meeting of the five permanent UN Security Council members and Germany on Iran in Berlin on Thursday. On the military option, an international opinion poll showed that most French and Americans would support military action as a last resort if other means fail to stop Iran getting the bomb.
The annual Transatlantic Trends survey, conducted for the German Marshall Fund of the United States, found 53 percent of Americans and 43 percent of Europeans supported taking military action rather than accepting a nuclear Iran.
"I don't see these high numbers as indicative of a European desire to support military attacks on Iran," US Assistant Secretary of State for European and European Affairs Daniel Fried told reporters at a launch of the poll in Berlin.
"To me that simply means that European publics are serious about dealing with the problem of Iran's nuclear weapons ambitions," he said.
Tehran, the world's fourth largest oil exporter, says its enrichment of uranium is a legal and peaceful programme.
Russian Foreign Minister Sergei Lavrov said any sanctions would be governed by the UN charter which "states unequivocally that economic measures exclude the use of force". Lavrov said the need for sanctions against Iran depended on whether it posed a real threat to international security.
Russia and China, permanent veto holders in the Security Council, do not regard Iran as a major threat, unlike the Bush administration. They also dislike the idea of sanctions.
Concern that Iran could halt its oil exports if put under more pressure over its nuclear programme have helped push oil prices higher in recent weeks.