Iranian President Hassan Rouhani says he wants to reach a deal with world powers on Tehran's nuclear programme in three to six months.
He told the Washington Post he saw a resolution of the issue as a "beginning point" in easing US-Iran relations.
Mr Rouhani said he was fully empowered by Iran's supreme leader, Ayatollah Khamenei, to negotiate on the issue.
On Thursday, Iran will hold talks with the P5+1 group of world powers on Tehran's uranium enrichment programme.
In a rare encounter between US and Iranian officials, Foreign Minister Mohammad Javad Zarif will meet US Secretary of State John Kerry as well as diplomats from the UK, France, Russia, China and Germany in New York.
On Tuesday, Mr Rouhani told the UN General Assembly that he was prepared to engage in "time-bound and results-oriented" talks on the nuclear issue.
Iran has been negotiating with the five permanent members of the UN Security Council, plus Germany, since 2006 about its nuclear programme.
The West suspects Tehran is trying to develop a nuclear weapon, a claim strongly denied by Iran.
'Everything is possible' Asked about a timeframe for resolving the nuclear issue, President Rouhani told the Washington Post: "The only way forward is for a timeline to be inserted into the negotiations that is short.
"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."
Despite years of hostility between the US and Iran, Mr Rouhani said that if he and President Barack Obama got together they would both be "looking at the future".
"The notes and letters and exchanges between us are in that direction, and they will continue," he said.
"We need a beginning point. I think that is the nuclear issue."
He added: "After resolution of the nuclear issue there are no impossibilities in term of advancing other things forward. Everything is possible after the settlement."
President Obama has welcomed the new Iranian president's more "moderate course".
He said the US wanted to resolve the nuclear issue peacefully, but was determined to prevent Iran from developing a nuclear weapon.
On Wednesday, Mr Zarif met French Foreign Minister Laurent Fabius on the sidelines of the General Assembly.
He said they "had a good discussion about the start of nuclear talks and the talks that will take place tomorrow".
Iran's economy has been badly affected by years of sanctions imposed by the UN and Western countries over the nuclear issue.