"The only way forward is for a timeline to be inserted into the negotiations that's short -- and wrap it up," Hassan Rouhani told The Washington Post in New York through an interpreter.
"That is a decision of my government, that short is necessary to settle the nuclear file," he said. "The shorter it is, the more beneficial it is to everyone. If it's three months, that would be Iran's choice. If it's six months, that's still good. It's a question of months not years."
Rouhani didn't say why Iran suddenly wanted a swift timeline, after years of disagreement and defiance. The Post speculated the desire for speed might reflect the pressure of U.S. sanctions on Iran's economy or Rouhani's fear of a political backlash from conservative rivals.
Iranian Foreign Minister Mohammad Javad Zarif is to meet on the nuclear issue Thursday with U.S. Secretary of State John Kerry and negotiators from Britain, France, Russia, China and Germany -- the so-called P5-plus-1 group of the five permanent U.N. Security Council members plus Germany.
The meeting is to be the first official face-to-face foreign minister meeting between the United States and Iran since 2000.
When asked what Iran hoped would result from the P5-plus-1 talks, Zarif told reporters, "a jump-start to the negotiations ... with a view to reaching an agreement within the shortest span."
He also said Iran had "the political readiness and political will for serious negotiations, and we are hopeful that the opposite side has this will as well."
In Washington, White House spokesman Jay Carney was asked at a briefing about Zarif's comment.
"We certainly have the will. We've demonstrated it for many years now," Carney said.
When asked if the administration also had the readiness, Carney said: "In the past, no. And I think that the comments [from Zarif] ... demonstrate certainly a different rhetorical approach to this problem that this new government is taking.
"And I think, as we've said, that is absolutely worth exploring and testing, so that we can discover -- we, the United States and our allies -- can discover whether or not they're serious and whether or not we can resolve this conflict diplomatically."
Washington and its allies allege Iran is well along toward developing a nuclear weapon, but Tehran insists its nuclear activities are only to produce electricity and for medical research.
President Obama, in his U.N. General Assembly address Tuesday, embraced a diplomatic opening with Iran, saying he instructed Kerry to begin the high-level negotiations on its nuclear program.
"The roadblocks may prove to be too great, but I firmly believe the diplomatic path must be tested," Obama said.
Rouhani told the Post he was prepared to offer extensive "transparency" measures to restore Western confidence Iran doesn't intend to develop a bomb.
"If the West recognizes Iran's legal rights, then there's really no hurdle in creating full transparency that's necessary to settle this case," he said.
Obama told the General Assembly, "We respect the right of the Iranian people to access peaceful nuclear energy." He added, "We should be able to achieve a resolution that respects the rights of the Iranian people, while giving the world confidence that the Iranian program is peaceful."
Rouhani said he believes if Iran and the P5-plus-1 can resolve the nuclear issue, then Tehran and Washington can discuss broader issues of normalizing relations after 33 years.
"We need a beginning point," Rouhani said.
"After resolution of the nuclear issue, there are no impossibilities in terms of advancing other things forward," he said. "The foundation for all this is the confidence that has to be built. That clearly will help everything else. Everything is possible after the settlement."