US President Donald Trump has blamed the Islamic republic's refusal to abandon its nuclear ambitions for the collapse of the talks.

"Both sides are sincere about the ceasefire," Hakan Fidan said in an interview with the official Anadolu news agency, adding that he has been in contact with the parties involved in the negotiations.

"I am thinking that if the nuclear issue comes down to an all-or-nothing situation especially regarding enrichment, we might face serious obstacles," Fidan said.

"Hopefully, we will try to overcome this with the support of some mediators," he added.

Turkey, while a fierce critic of Israel, joined diplomatic efforts with Egypt and Pakistan to reach a ceasefire in the conflict.