Iran's president has ordered a probe into the "conspiracy" of leaked audio in which the foreign minister says the military was too influential in diplomacy, a government spokesman announced Tuesday.

President Hassan Rouhani ordered the investigation to identify who leaked the "stolen" three-hour-long recording by top diplomat and member of his moderate government Mohammad Javad Zarif, the spokesman said.

The tape, which comes ahead of presidential elections in June, has dominated the discussion in the Islamic republic since its publication by media outlets outside Iran on Sunday.

"We believe this theft of documents is a conspiracy against the government, the system, the integrity of effective domestic institutions, and also against our national interests," government spokesman Ali Rabiei told reporters.

"The president has ordered the intelligence ministry to identify the agents of this conspiracy," he added.

The file was "stolen for clear reasons", he said, without elaborating further.

Foreign ministry spokesman Saeed Khatibzadeh did not deny the authenticity of the recording but said on Monday that it was cut from a seven-hour interview that included "personal opinions".

Zarif did not comment on the controversy, but published on Tuesday a brief audio message on Instagram, saying "I believe you should not work for history... I say that don't worry about history so much, but worry about God and the people".

He did not specify when he recorded this message.

The leaked remarks sparked harsh criticism from conservative media and politicians, with the mention of Iran's slain general Qasem Soleimani hitting a nerve.

Soleimani, considered one of the prominent architects of Iranian regional policy, was killed early last year in an American drone strike in Baghdad, ordered by former US president Donald Trump.

The leak and probe come ahead of presidential elections on June 18, which will see the moderate Rouhani step down after two terms in office and after conservatives fared well in parliamentary elections last year.

Character assassination

The ultra-conservative Vatan-e Emrooz newspaper published a large black and white picture of Zarif on its front page, with the headline "Despicable" written in red.

"Diplomacy must follow the path of increasing the system's power," it said, criticising Zarif's comments regarding the military.

It added that his stance confirmed that "America's constant demand about negotiating Iran's regional power and missile capabilities" stemmed from Iranian diplomats' "wishes and cooperation with this demand".

Javan daily said Soleimani was "physically assassinated (upon) the order of the most wretched creature of the world... America's president".

But Zarif had "assassinated (Soleimani's) character".

Ultra-conservative Kayhan daily inferred that the audio may have been leaked by Rouhani's government to force "Zarif into (political) suicide" in a bid to save itself from the judgement of "public opinion".

It said Zarif, while being "sacrificed like a simple pawn", had broken rules of "confidentiality" and provided Iran's enemies with "intelligence and ammunition" for their psychological war against the country.

For their part, the reformist papers sought to question which faction stood to gain from the leak.

Shargh daily on its front page wrote "Who leaked it, who benefited?"