"It goes counter to the decisions of the International Atomic Energy Agency and the statement of the U.N. Security Council," a ministry spokesman was quoted as saying.
However, Iran promptly rejected the Russian call that it end its uranium enrichment work, saying its nuclear program could not be stopped.
"Iran's nuclear activities are like a waterfall which has begun to flow. It cannot be stopped," a senior Iranian official told Reuters on condition of anonymity when asked about Russia's demand.
U.N. nuclear watchdog chief Mohamed ElBaradei said Wednesday upon arrival in Tehran that he hoped to persuade Iran to suspend its uranium enrichment activities.
"We hope to convince Iran to take confidence-building measures including suspension of uranium enrichment activities until outstanding issues are clarified," ElBaradei told journalists at the Tehran airport.
"I would like to see Iran has come to terms with the request of the international community," he added.
Long history of deception
ElBaradei said that depsite the escalation in tensions he hoped the nuclear crisis still could be resolved through political dialogue.
"I am hopeful the time is right for political solutions, through negotiations. I hope conditions will be created for all parties to return to talks," he said.
ElBaradei is due Thursday to meet Iran's chief negotiator on the nuclear issue, Ali Larijani, as well as vice president and atomic energy chief Gholam Reza Aghazadeh. He must give a report at the end of April on Iran's nuclear activities to the U.N. Security Council and the 35 states of the IAEA's governing council.
Responding to the recent Iranian statements, White House spokesman Scott McClellan said on Tuesday that these illustrate why the international community was worried over Iran's nuclear ambitions.
Iran's regime ``needs to build confidence with the international community,'' McClellan said. ``Instead, they're moving in the wrong direction.''
“This is a regime that has a long history of hiding its nuclear activities from the international community, and refusing to comply with its international obligations. Defiant statements and actions only further isolate the regime from the rest of the world, and further isolate the Iranian people,” McClellan said.
Iran's President Mahmoud Ahmadinejad declared on Tuesday the Islamic republic has reached a key step in its nuclear program and that it will "soon join the club of countries that have nuclear technology."
"The equation will change in favor of the Iranian people," Ahmadinejad said in a speech in the northeast of the country.