Iran's new government, stepping up a campaign to project a more moderate image abroad, said on Wednesday it wants to jump-start talks with world powers to resolve a decade-long dispute over its nuclear program and hoped for a deal in three to six months.

Iranian Foreign Minister Mohammed Javad Zarif is set to hold talks on the nuclear issue on Thursday with U.S. Secretary of State John Kerry as well as diplomats from Britain, France, Russia, China and Germany, in a rare encounter between top American and Iranian officials.

"The only way forward is for a timeline to be inserted into the negotiations that's short," new Iranian President Hassan Rohani was quoted as telling the Washington Post, through a translator, during a visit to New York, where he addressed the United Nations General Assembly on Tuesday.

"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," said Rohani when asked for a time frame for resolving Iran's nuclear dispute with the West.

Earlier on Wednesday, Iran's foreign minister expressed hope for a quick resolution of the nuclear stand-off.

Asked what he expected from Thursday's meeting with the five permanent UN Security Council members plus Germany, Zarif told reporters: "a jump-start to the negotiations ... with a view to reaching an agreement within the shortest span."

Speaking after a meeting with French Foreign Minister Laurent Fabius on the sidelines of the UN General Assembly, he added: "The Islamic Republic has the political readiness and political will for serious negotiations and we are hopeful that the opposite side has this will as well."

"We (Zarif and Fabius) ... had a good discussion about the start of nuclear talks and the talks that will take place tomorrow at the foreign ministerial level between Iran and the P5+1," Zarif said, referring to the so-called P5+1 group comprising the five Security Council powers plus Germany.

U.S. President Barack Obama on Tuesday cautiously embraced overtures from Rohani, a new centrist president, as the basis for a possible nuclear deal and challenged him to take concrete steps toward resolving the issue.

Iran has been negotiating with the P5+1 since 2006 about its nuclear program, which Western powers and their allies suspect is aimed at developing a nuclear-weapons capability. Iran says its nuclear program is for peaceful civilian energy purposes only.