In a statement, foreign ministers from the UN Security Council's five permanent members and Germany said the Iranians had given no indication at all that they were ready to engage seriously on the substance of their proposals.
French Foreign Minister Philippe Douste-Blazy said: "We have agreed to seek a United Nations Security Council resolution, which would make the IAEA-required suspension mandatory.”
”Should Iran refuse to comply then we will work for the adoption of measures under Article 41 of Chapter Seven of the United Nations charter.”
The article in question opens the way for economic and diplomatic sanctions if Iran refuses to suspend uranium enrichment, but not for the use of military force.
Solana addressed meeting
The ministers had met to hear a progress report from the EU's foreign policy chief Javier Solana, who the day before held talks in Brussels with Tehran's top nuclear negotiator Ali Larijani.
The six are pushing for a positive Iranian response to a package of economic and political incentives offered on June 6, but EU officials described Tuesday's meeting as "disappointing".
Iran insists on the right to continue uranium enrichment, arguing that it is needed for a civilian nuclear energy programme, but the outside powers suspect Tehran is trying to make nuclear weapons and the Vienna-based International Atomic Energy Agency has ordered a suspension.
The ministers said that; "Should Iran implement the decisions of the IAEA and the United Nations Security Council, and enter into negotiations, we would be ready to hold back from further action in the UN Security Council."
"We are very pleased by today's strong action," deputy US Secretary of State, Nicholas Burns, said afterwards.
Referring to the six countries at the talks he said: "We are all frustrated, we are deeply disappointed, (the Iranians) are giving us nothing," he said.
A senior US official said top foreign ministry officials of the six countries would meet next week to decide how long to give Tehran before resorting to sanctions, adding the specific sanctions had not yet been decided.
Draft resolution "next week"
Later, the US Ambassador to the UN John Bolton said he hoped the Security Council would be able to take action "early next week" on a draft resolution that would make a halt to Iran's uranium enrichment mandatory.
On Tuesday, Iran's negotiator Ali Larijani said the offer of incentives - which reportedly include aid for a civilian energy programme and an end to some US sanctions - was "broadly suitable" but that suspending enrichment remained a central problem.
On Wednesday, Iranian President Mahmoud Ahmadinejad repeated that Iran would not negotiate on its "undeniable right" to have a nuclear programme.
"We are for negotiations, we are for dialogue. But of course we will not negotiate our undeniable rights with anyone," he told a public rally.
Iran may 'revise' cooperation
The Iranian President Mahmoud Ahmadinejad has threatened to revise the country's cooperation with international authorities looking into Iran’s controversial nuclear program, after world powers referred the issue back to the United Nations Security Council.
"If they (Western powers) create tension, they will be responsible for the consequences because the Iranian people will continue their legal path," the president was quoted as saying by state television.
"Up to now, the path that we had chosen was a path of peace and in the framework of the regulations. They should know that if the Iranian people feel that they are not sincere, they (the Iranian people) will revise their policies," he warned.
‘wrong’ decision
The official news media on Thursday condemned as "wrong" that decision, commentary carried by IRNA said the move was made "under US influence" and would send the crisis into the "depths of an abyss".
The station also condemned what it described as "serious double-standards in an effort to demolish the absolute right of a nation that has on hundreds of occasions emphasised its nuclear programme is merely aimed at absolutely peaceful purposes."
The decision to refer Iran back to the UN Security Council came after the government failed to respond to an offer of trade, technology and diplomatic incentives in exchange for a suspension of uranium enrichment work.
Iran says it wants to enrich uranium to make reactor fuel, but the United States fears it could also be used to develop a nuclear weapon.