"There is no compromise, new Russian proposal," Russian Foreign Minister Sergei Lavrov said following talks with US Secretary of State Condoleezza Rice.
"There is no compromise proposal, and could not be any compromise proposal," he said.
Compromise claims
Diplomats in Vienna had earlier claimed that Russia had proposed a plan under which Iran would be allowed to conduct research on small quantities of uranium, without gaining the technology it needs for large-scale enrichment that could be diverted for weapons use.
Ms Rice said the Russian delegation "did not tell us of any new proposal that they have made to the Iranians concerning anything but the February 4 resolution."
Under the resolution mentioned by Ms Rice the International Atomic Energy Agency (IAEA) has demanded an immediate halt to all of Iran's nuclear work.
Mr Lavrov said Iran's program, which the United States says is being used to hide nuclear weapons development, would be sent to the UN Security Council by the IAEA.
Iran is ready to hold off on industrial-scale enrichment for two years, according to unnamed diplomat, but refuses to suspend small-scale work believed to have less of a proliferation risk.
Mr Lavrov was believed to be referring to the fact that Russia would at first insist on full suspension of enrichment by Iran, in order to start talks. But eventually the deal could lead to Iran doing research on the strategic process.
Iran views research work as involving up to 3,000 centrifuges, the machines which enrich uranium, but experts say that is an industrial-level figure.
US concerns
The United States restated its view that Iran has already "crossed the international red line."
"We've made it very clear, as have many in the international community, that the regime must suspend all enrichment activity," White House spokesman Scott McClellan said in Washington.
Mr McClellan said that after the IAEA meeting, Washington expected the nuclear dossier to move to the UN Security Council.
The IAEA's 35-nation board of governors was due to hear a report on Iran on Wednesday.
The 15-page report by IAEA chief Mohamed ElBaradei says that Iran has failed to heed IAEA calls for it to suspend uranium enrichment and to cooperate fully with IAEA inspectors.
Resolving this issue would open the way for Iran to restart talks with the so-called EU-3, Britain, France and Germany, on guaranteeing it is not seeking nuclear weapons.