Iran's deputy foreign minister stated on Saturday that no date has been set for the next round of talks with the United States, emphasizing that a framework for understanding must first be established.

The highest-level U.S.-Iran talks since the 1979 Islamic Revolution ended in Islamabad without agreement last weekend, The Caspian Post reports, citing foreign media.

U.S. President Donald Trump has told Reuters there would probably be more direct talks this weekend, though some diplomats said that was unlikely given the logistics of convening in Islamabad, where the talks are expected to take place.

"We are now focusing on finalising the framework of understanding between two sides. We don't want to enter into any negotiation or meeting which is doomed to fail and which can be a pretext for another round of escalation," Saeed Khatibzadeh told reporters on the sidelines of a diplomacy forum in the southern Turkish province of Antalya.

"Until we agree the framework, we cannot set the date... There was significant progress made actually. But then the maximalist approach by the other side, trying to make Iran an exception from international law prevented us to reach an agreement," he said, referring to U.S. demands over Iran's nuclear programme.

"I have to be very crystal clear that Iran would not accept to be an exception from the international law. Anything that we are going to be committed will be within the international regulations and international law."

Asked about reports that Iran again closed the Strait of Hormuz on Saturday after its temporary reopening following a separate U.S.-brokered 10-day ceasefire between Israel and Lebanon on Thursday, Khatibzadeh said Iran had announced it would allow the safe passage of commercial vessels in line with the terms of the truce.