"Ultimately, we were able to reach broad agreement on a set of guiding principles, based on which we will move forward and begin working on the text of a potential agreement," Araghchi told state TV.

"I can say that, compared with the previous round, fully serious discussions were raised and the atmosphere was more constructive," he added.

Tehran and Washington held on Tuesday a second round of negotiations -- which began earlier this month -- after talks last year collapsed following Israel's attack on Iran in June, which triggered a 12-day war.

That war saw the United States briefly join Israel with strikes on key Iranian nuclear sites.

The latest talks were held after Washington deployed an aircraft carrier group to the Middle East following Iran's deadly crackdown last month on anti-government protests, first sparked by economic hardships.

During the interview with state TV, Araghchi said the two sides have begun a path towards an agreement, but noted that "this does not mean we can reach a deal quickly".

"We hope this process can be completed as soon as possible and we are ready to devote sufficient time to it," he added.

He acknowledged that it "will take time to narrow" the gap between the positions of both sides, "but at least we now have a set of guiding principles and a clearer path to move forward on".