The negotiations took place on Saturday in Pakistan against the backdrop of a fragile two-week ceasefire announced days earlier that offered a lull in the bombing.

"I really wanted them to make peace," said Mahsa, a 30-year-old employee of an export company in the Iranian capital.

"It's been almost 45 days now that I've seen everyone stressed. It's a bad situation."

The United States and Israel attacked Iran on February 28, sparking retaliation from the Islamic republic that has plunged the Middle East into conflict and shaken the global economy.

Hours before the announcement of the ceasefire, US President Donald Trump warned that "a whole civilisation will die... never to be brought back again" as he threatened to bomb infrastructure across Iran.

"I was stressed until 3:00 am... No one slept that night," Mahsa said.

It was not immediately clear whether the two sides would resume talks after Saturday's discussions failure, or whether the ceasefire would hold.

- 'No other way but war' -

The main sticking points were not officially disclosed at the time, but Trump later castigated Iran for not opening the Strait of Hormuz and said it had refused to concede on the issue of its nuclear programme.

The weeks of bombardment have taken a huge toll on Iranians.

"We feel despair and hopelessness. We are tired of this uncertainty," said Nahid, a 60-year-old housewife in Tehran.

Although disappointed, 42-year-old shop owner Farhad said he had expected the talks to fail.

"We knew from the beginning that the other side did not want to reach a conclusion," he said, referring to the United States.

Hamed, 37, said the failure to reach a deal signalled more fighting ahead.

"I would have preferred peace, but I think there is no other way but war and confrontation," he said.

"Based on what I see and hear, unfortunately we are going to war again and it seems like we will have a long war."