President Barack Obama promised to launch a new diplomatic push to solve the longstanding crisis over Iran's disputed nuclear program, saying there was still a "window of time" to end the standoff.

His comments came amid speculation about possible direct US talks that surfaced just before the US elections and has gone up in volume since Obama's reelection.

Iran, reeling from international sanctions over its nuclear program, has not ruled out direct talks with Washington but says these will not come overnight.

"With respect to Iran, I very much want to see a diplomatic resolution to the problem," Obama told a White House press conference.

"I will try to make a push in the coming months to see if we can open up a dialogue between Iran and not just us, but the international community, to see if we can get this thing resolved."

Though he was careful to stress that Washington remains adamantly opposed to letting Iran obtain a nuclear weapon, Obama added: "There is still a window of time for us it resolve this diplomatically."

He cited crippling sanctions imposed on Iran by the UN Security Council and unilateral Western restrictions on Tehran's oil sector and banks, calling them the "toughest sanctions in history."

Iran insists it is developing nuclear energy for peaceful, civilian purposes, but Israel and Western nations fear the program is a cover for a drive to produce nuclear weapons.

"There should be a way in which they can enjoy peaceful nuclear power while still meeting their international obligations and providing clear assurances to the international community that they're not pursuing a nuclear weapon," Obama said. "I can't promise that Iran will walk through the door that they need to walk through. But that would be very much the preferable option."

Obama nonetheless denied that talks with Iran were imminent.

"I think it is fair to say that we want to get this resolved and we're not going to be constrained by diplomatic niceties or protocols if Iran is serious about wanting to resolve this," the president added.

Iranian Foreign Minister Ali Akbar Salehi said Monday that any "decision on comprehensive, bilateral political talks between the two countries... is up to the supreme leader," Ayatollah Ali Khamenei.

Russia's representative in international talks with Iran over its disputed nuclear program, Sergei Ryabkov, was quoted as telling The Financial Times that Moscow would support direct talks between Iran and the United States.

Salehi also expressed hope that negotiations on its nuclear program with the so-called P5+1 -- the UN Security Council's five permanent members Britain, China, France, Russia and the United States plus Germany -- would resume soon.

The P5+1 has for years sought to defuse an international crisis over Tehran's atomic ambitions through negotiations with the Islamic republic.

The last high-level talks, which all but failed, were held in Moscow in June.

The UN atomic watchdog has said it will hold a new round of talks in Tehran on December 13.