Ali Akbar Salehi, Iranian Vice-President and head of Atomic Energy Organization of Iran, speaks during the 57th General Conference of the International Atomic Energy Agency (IAEA) in Vienna, capital of Austria, on Sept. 16, 2013. (Xinhua/Qian Yi) 

 
Iranian Foreign Minister Mohammad Javad Zarif said on Tuesday there is a "historic opportunity" to resolve Iran's decade-long nuclear showdown with world powers.

"We have a historic opportunity to resolve the nuclear issue," if world powers adjust to the "new Iranian approach," Zarif said, without elaborating, in a tweet from New York where he is attending the UN General Assembly.

His comments come a day after he met EU foreign policy chief Catherine Ashton in New York on restarting nuclear talks with the so-called P5+1 group - United States, Britain, France, China and Russia plus Germany.

US President Barack Obama told the UN General Assembly on Tuesday that the US wants to resolve the Iran nuclear issue peacefully but is determined to prevent Iran from developing a nuclear weapon.

"The roadblocks may prove to be too great but I firmly believe the diplomatic path must be tested," Obama said.

Iran's new President Hassan Rouhani has promised constructive engagement and increased transparency over the program in exchange for the easing of crippling international sanctions.

Rouhani is expected to address the General Assembly later Tuesday, in a speech closely followed by the West for confirmation that the moderate president's pledge is real.

Zarif on Thursday will join counterparts from the P5+1, including US Secretary of State John Kerry at the meeting at United Nations headquarters, marking the first time the two arch-foes discuss Iran's nuclear ambitions at ministerial level.

The meeting bringing the top US diplomat and new Iranian foreign minister around the same conference table will be highly unusual given the US has not maintained diplomatic relations with Iran since 1980.

US officials have also said a meeting is possible this week between Obama and Rouhani.

"Such a meeting is not on the agenda," Iranian foreign ministry spokeswoman Marzieh Afkham told reporters after the White House did not rule out the possibility.