The official Islamic Republic News Agency reported only that a US warship "claimed" to have saved the Iranian fishermen from a weeks-long ordeal as captives of Somali pirates.
"So far Iran's armed forces staff has not confirmed" the incident, IRNA said.
The US military said the rescue was carried out on Thursday by the USS Kidd, one of several warships escorting the aircraft carrier USS John C. Stennis, after the captain of the Iranian fishing dhow asked for help.
On Tuesday, Iranian military chiefs had warned the Stennis, which is currently attached to the US Fifth Fleet based in Bahrain, to stay out of the Gulf. Otherwise it would face the "full force" of Iran's navy, spokesman Commodore Mahmoud Mousavi said.
A New York Times reporter and photographer, who were travelling on the Stennis, went aboard the Iranian fishing vessel, Al Mulahi, and spoke with its crew, as well as with several of the Somali pirates arrested by the Americans.
"It is like you were sent by God," one of the Iranian fishermen, Fazel Ur Rehman, 28, was quoted as telling his US rescuers.
The captain, Mahmed Younes, 28, told the New York Times 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.
A Pentagon spokesman, Captain John Kirby, said the Iranians and their dhow were released to make their way back to Iran, with fuel and provisions supplied by the Stennis's carrier group.
The rescue came at a delicate time in the West's longrunning showdown with Iran over its nuclear programme, with Washington and its allies ramping up sanctions to try secure a change of heart from Tehran.
Iran has reacted by threatening to close the Strait of Hormuz, which links the Gulf to the Arabian Sea, and has warned against the Stennis's redeployment to the Gulf.
The United States has said it will not tolerate any closure of the strait -- through which 20 percent of the world's oil flows -- and has insisted that it will continue to deploy warships to the Gulf.