US President George W Bush has said he believes Iran will be referred to the UN Security Council for sanctions if it does not "live up to its agreements".
The two leaders stressed their common views on the nuclear issue
Russian President Vladimir Putin, speaking with Mr Bush in Washington, said he agreed that Iran should not become a nuclear power.
Iran argues its nuclear programme is only for civilian purposes.
Its president, Mahmoud Ahmadinejad, is set to raise the issue in a speech at the United Nations on Saturday.
The UN's nuclear watchdog, the International Atomic Energy Agency (IAEA) is due to meet in Vienna on Monday and could decide to refer Iran to the Security Council.
The European Union, which has been engaged in talks with Tehran, has already signalled that it is preparing to take the matter to the UN.
Russia, which has the power of veto on the Security Council, has been calling for more diplomacy.
However, the BBC's Jonathan Beale in Washington says Mr Bush and Mr Putin tried to present a united front following their talks at the White House.
"I am confident that the world will see it to it that Iran goes to the UN Security Council if it does not live up to its agreements," Mr Bush said.
"When that referral will happen is a matter of diplomacy and that's what we talked about. We talked about how to deal with this situation diplomatically."
Mr Putin said Russia would continue to co-operate in dealing with both North Korea as well as Iran's nuclear ambitions, though he added that diplomacy was far from exhausted.
"The potential of diplomatic solutions to all these questions is far from being exhausted," the Russian president said.
"And we will undertake all of the steps necessary to settle all of these problems and issues, not to aggravate them."
Iranian President Mahmoud Ahmadinejad, a hardliner elected in June, is expected to set out his proposals to address international concerns in his speech at the United Nations.
Earlier this week, on the sidelines of the UN summit in New York, he met the British, French and German foreign ministers in the highest-level talks on the subject since his election.
UK Foreign Secretary Jack Straw said they wanted to avoid referring Iran to the UN Security Council.
Iran has insisted it has the right to pursue a civilian nuclear programme for peaceful purposes, but the US suspects it of pursuing a nuclear weapons programme.