Iran's President Hassan Rouhani said Wednesday a breakthrough in talks in Vienna to revive a nuclear deal before he leaves office in August requires a "will" beyond his power.

Rouhani is Iran's main architect of the 2015 nuclear agreement with world powers, which was torpedoed by former US president Donald Trump in 2018.

But the final decision regarding the ongoing Vienna negotiations rests with Islamic republic's supreme leader Ayatollah Ali Khamenei.

"Our main issues with the United States in these negotiations have been resolved, and there are only a few minor issues left, on which we will negotiate and produce results," Rouhani said, at a televised cabinet meeting.

"If there is the will that this be done in the current administration, then this administration has finished the work," he added.

Iranians vote on June 18 for a new president, with Rouhani having served the maximum two consecutive terms allowed under the constitution. He will hand over power in August.

Negotiations have been underway since April in the Austrian capital between Iran and the remaining members to the accord, Britain, China, France, Germany and Russia. 

Washington is participating indirectly.

Trump's successor, US President Joe Biden, has signalled his readiness to revive the nuclear deal.

For this to happen, the US would need to return to the accord and lift the sanctions reinstated by Trump, while Tehran would have to re-commit to full compliance with nuclear obligations it progressively withdrew from since 2019 in retaliation.

Sanctions reimposed by Trump deprived Iran of the economic benefits the deal had promised, especially by blocking its vital oil export lifeline and access to its funds abroad, sparking an economic crisis.