Western powers have said they will push for a legally binding UN resolution to force Iran to comply with calls for it to cease uranium enrichment.
US ambassador John Bolton said there was a sense of urgency about the move.
On Friday the UN's nuclear watchdog said in a report that Tehran had ignored Security Council calls.
Iran said it was willing to find a constructive solution but would not respond to pressure from the international community.
The UN wants the research halted amid Western fears - denied by Iran - that Tehran might develop nuclear weapons.
The stage is set for months of diplomatic confrontation, the BBC news website's world affairs correspondent Paul Reynolds says.
US President George W Bush said the report showed Iran's intransigence and the United States would continue to consult its allies over what he termed Iran's nuclear weapons ambitions.
Mr Bolton said it was clear that Iran had accelerated its nuclear programme and that he hoped the Security Council would act as soon as possible.
"We do think there's a sense of urgency here and we hope that we can get council action just as soon as possible," he said.
But UK ambassador Emyr Jones Parry said he would submit a draft resolution which, while making the demands legally binding, would not threaten sanctions or military force.
Security Council permanent members Russia and China oppose both sanctions and the use of force.
The Iranian ambassador to the UN, Javad Zarif, told the BBC Iran was willing to find a constructive solution.
"We want to avoid confrontation but at what price? ...We are not prepared to respond to pressure," he said.