A senior Russian envoy, Igor Ivanov, has met Iranian officials but denied reports he had given them a proposal aimed at ending the nuclear stand-off.
Iran faces the threat of sanctions if it does not halt its nuclear plans
Russian officials had spoken of a plan that would allow Iran to engage in uranium conversion while shifting the process of enrichment to Russia.
But Mr Ivanov, on a visit to Tehran, told Iranian television that Russia had not put forward any specific proposal.
Tehran argues that it has a legitimate right to peaceful nuclear technology.
It has given no hint that it is willing to consider a compromise that moves the most sensitive part of nuclear fuel production - enrichment - to another country, the BBC's Frances Harrison reports from Tehran.
Mr Ivanov's denial comes a day after Russian Foreign Minister Sergei Lavrov told reporters that Russia expected a swift response to its nuclear proposal.
He said Moscow was working closely with Europe, the US and the UN nuclear watchdog to find a political resolution to the issue.
'Change of attitude'
Mr Ivanov met Iran's top nuclear negotiator, Ali Larijani, on Saturday.
Mr Larijani said afterwards that instead of new proposals, what Iran needed was a change of attitude so that Iran's rights were recognised.
He added that if any proposals were put forward, then Iran would take them into consideration.
The West fears that the enrichment process could enable Iran to produce nuclear weapons-grade uranium.
In August Tehran rejected European proposals for resolving the crisis and resumed the processing of uranium.
The International Atomic Energy Agency (IAEA) in September paved the way for Iran's referral to the Security Council - which could impose sanctions - but the agency has not set a date for this.
The agency's board of governors is due to discuss the issue on 24 November.