The Iranian government has welcomed a US Navy rescue of 13 of its nationals from pirates near the entrance to the Gulf, in a rare respite from months of rising tensions between Tehran and Washington.

But one Iranian media outlet, the Fars news agency, which is close to the hardline Revolutionary Guards, dismissed the incident as a suspect "Hollywood movie" meant "to justify the presence of a (US) aircraft carrier in Persian Gulf waters."

The rescue was carried out on Thursday by one of several warships escorting the carrier USS John C Stennis, which Iranian military chiefs early this week warned to stay out of Gulf waters or else face the "full force" of Iran's navy.

"We consider the actions of the US forces in saving the lives of the Iranian seamen to be a humanitarian and positive act and we welcome such behaviour," foreign ministry spokesman Ramin Mehmanparast told Iran's Arabic-language broadcaster Al-Alam on Saturday.

"We think all nations should display such behaviour," he added.

The US military announced on Friday that one of the vessels escorting the Stennis, the USS Kidd, rescued the Iranian fishermen from around 45 days of captivity at the hands of pirates thought to be Somalis.

It said the Iranian captain of the dhow had asked the Kidd for help.

The pirates were taken into custody and the Iranian fishermen released to return home on their dhow, which was refuelled and restocked with provisions supplied by the US navy vessels.

The USS Kidd rescues Iranian fishermen from Somali pirates ( 7pm TV News NSW )

"Sent by God"

"It is like you were sent by God," one of the Iranian fishermen, Fazel Ur Rehman, 28, was quoted as telling his US rescuers.

A reporter for the New York Times newspaper who was travelling travelling on the Stennis boarded the Iranian fishing vessel, the Al Mulahi, and spoke with its crew and several of the pirates.

The Iranian captain, Mahmed Younes, 28, said the pirates had captured his vessel in late November and had since been using it as a mother ship for their operations around the region.

Photographs of the Iranian dhow and crew, and of the arrested pirates, were published on the New York Times website.

Iran's official IRNA news agency initially said a US warship had only "claimed" to have carried out the rescue, and that Iranian military leaders had not confirmed it.

The Fars news agency then reported that the rescue was nothing more than a "Hollywood movie" that was the object of a "media blitz" by the Pentagon.

"Iran's navy has on so many occasions rescued foreign ships from pirates, but they have never been praised and hailed by foreign media, not that Iranian navy officials were looking for propaganda," Fars said.

"There is suspicion and doubt about this American action, which seems to have been pre-organised," it said.

"It was more like a Hollywood film with a fixed location and specific actors," said Fars, highlighting that the US navy had provided video of the incident.

"This shows the Americans were looking at using it for propaganda advantage," it added.

In recent weeks, the United States and Iran have been sliding deeper into a showdown over the Gulf, and particularly the narrow Strait of Hormuz at its mouth, through which 20 per cent of the world's oil flows.

Ramped-up Western sanctions have prompted Iran to threaten to close the waterway.

Last Tuesday, Iranian military leaders warned the Stennis, which is currently attached to the US Fifth Fleet based in Bahrain, to stay out of the Gulf.

The US military responded that it would continue to deploy its warships to the Gulf. It has also said it will "not tolerate" closure of the Strait of Hormuz.

AFP