The UN Security Council has unanimously passed a resolution that orders Iran to halt nuclear enrichment work, but imposes none of the new sanctions Washington and its allies want.
The resolution was adopted on Saturday after the text had been agreed on Friday by the five permanent Security Council members - Britain, China, France, Russia and the United States - plus Germany on the sidelines of the UN General Assembly.
The 18-line resolution calls on Iran to "comply fully and without delay" with previous council resolutions, which demand it halt enrichment, but also "reaffirms its commitment ... to an early negotiated solution to the Iranian nuclear issue."
It also urges Iran to meet the requirements of the UN International Atomic Energy Agency (IAEA) in Vienna, which is investigating whether Iran had conducted research on an atomic weapon.
The agency reported earlier this month Iran was not co-operating, but Tehran says it has been.
Iran, which insists its nuclear programme is entirely peaceful and will only be used to generate electricity, dismissed the resolution.
"These [resolutions] are not constructive," Iran's chief nuclear negotiator, Saeed Jalili, told Iranian television.
"What they need to do is to attract the trust of the Iranian nation through constructive co-operation and collective commitment," he said.
He also said the text could mean that the six powers were no longer united on the issue of Tehran's nuclear programme.
Divisions among the powers have been clear for some time.
The United States, Britain and others accuse Tehran of stonewalling the IAEA and had wanted the council to pass a resolution imposing a fourth round of sanctions against Iran.
Russia and China gave reluctant backing to three previous sanctions resolutions that included asset freezes and travel bans on specific Iranian individuals and companies but are blocking further measures for the time being.
Sergei Lavrov, Russia's foreign minister, whose country has veto power on the Security Council, appeared to rule out new sanctions in the near future.
"[We] continue to believe that it is not timely to consider at the ministerial, or at any other level, this proposal of new sanctions," Lavrov told a news conference on Friday.
Condoleezza Rice, the US Secretary of State, stressed the need to heal East-West rifts over Russia's invasion of Georgia and convince Iran that the six powers remained united.
David Miliband, British foreign minister, rejected the idea that the group was divided, telling reporters there was "no weakening at all in our resolve to ensure that Iran does not continue on the path towards a nuclear weapon".