In mid-June, Israel launched an unprecedented bombing campaign against Iran, triggering a war during which Iran responded with missile and drone strikes.

During the 12-day war, Israel targeted Iranian military and nuclear sites as well as residential areas, with the United States joining later with strikes on key nuclear facilities.

The conflict derailed nuclear talks between Tehran and Washington which had begun in April. A ceasefire between Iran and Israel has been in place since June 24.

In an interview published Wednesday with Swiss newspaper Le Temps, the head of the International Atomic Energy Agency (IAEA) Rafael Grossi said "if diplomacy fails, I fear a renewed use of force".

Iranian Foreign Minister Abbas Araghchi on Thursday said it was not clear whether Grossi's remarks were meant "out of concern or as a threat".

"But those who issue such threats must understand that repeating a failed experience will only lead to another failure," he added in a video published by the foreign ministry.

Tensions between Iran and the IAEA surged immediately after 12-day war, with Tehran suspending its cooperation with the agency over what it described as its failure to adequately condemn the Israeli and US strikes.

In September, Iran and the IAEA agreed a new cooperation framework, but weeks later Tehran deemed that framework invalid after Britain, France, and Germany triggered the return of UN sanctions that were removed under a 2015 nuclear deal.

That deal was effectively torpedoed in 2018 when the US unilaterally withdrew from it during President Donald Trump's first term in office.

During his interview, Grossi said Iran had since the war imposed "limits on inspections because it fears for its security" and only allowed inspectors "sparingly".

According to the IAEA, Iran is the only country without nuclear weapons to enrich uranium to 60 percent, close to the 90 percent threshold required for a bomb.

"If it were to take the next steps, Iran would have enough material for around 10 nuclear bombs," said Grossi.

"However, we have no proof that Tehran was seeking to acquire nuclear weapons."