"There is no question of returning to a new suspension at Isfahan," Manouchehr Mottaki said on Sunday.
Iran's decision last month to resume uranium conversion work at Isfahan has scuttled talks with Britain, France and Germany intended to win guarantees that Iran's nuclear programme is peaceful.
This has led to threats from US and EU leaders to ask the International Atomic Energy Agency (IAEA), when it meets in Vienna on 19 September, to refer Iran to the Security Council.
A final week of diplomacy begins on Monday before the crucial 19 September meeting.
Diplomats close to the IAEA said that intense back-door negotiations in capitals as well as at IAEA headquarters in Vienna were under way to resolve the crisis over what the US says is a secret Iranian drive to develop nuclear weapons.
US Secretary of State Condoleezza Rice last week issued an open appeal to China, Russia and India to support the US drive to have the IAEA bring Iran before the Security Council, which could impose sanctions on the Islamic Republic.
Rice appealed to countries to
bring Iran before the UN
Rice said seeking UN action against Tehran was a "reasonable option" after the Iranians last month resumed fuel cycle work they had voluntarily suspended in November 2004 as part of negotiations with Britain, France and Germany.
"Iran needs to get a message from the international community that is a unified message, and by this I mean not just the EU-3 and the United States, but also Russia and China and India and others," Rice said.
Mottaki said Iran was "in favour of unconditional negotiations with the Europeans, and we will make an effort in this regard".
"There is no legal basis to send the dossier to the Security Council. This would be a political move. We do not see a serious sign that this will happen," said Mottaki, speaking at his first news conference since taking his post.
"It is natural that such an event will have consequences, but right now I do not want to go into what the repercussions would be," he added.