Iran denied on Thursday that its Revolutionary Guards launched rockets near the US aircraft-carrier Harry S. Truman and other warships as they were entering the Gulf on Saturday.

"The naval forces of the Guards have not had any exercises in the Strait of Hormuz during the past week and the period claimed by the Americans for them to have launched missiles and rockets," the Revolutionary Guards website quoted Ramezan Sharif, the Guard's spokesman, as saying.

"The publication of such false news under the present circumstances is akin to psychological warfare," Sharif said.

NBC News, citing unnamed US military officials, said the Guards were conducting a live-fire exercise and the Truman came within about 1,500 yards (metres) of a rocket.

In Washington, Navy Commander Kyle Raines, spokesman for the US Central Command, said on Tuesday several Revolutionary Guard vessels fired the rockets "in close proximity" of the warships and nearby merchant traffic "after providing only 23 minutes of advance notification".

"These actions were highly provocative, unsafe and unprofessional and call into question Iran's commitment to the security of a waterway vital to international commerce," Raines said.

Sharif said: "Preserving the security and peace of the strategic Persian Gulf region is among the serious strategies of Iran, and the Guards carry out their military exercises ... based on a set schedule."

The Truman, accompanied by two warships from the US-led coalition supporting air strikes against Islamic State militants in Iraq and Syria, was entering the Gulf through the Strait of Hormuz on a routine transit when the incident occurred, he said.

NBC News said the US destroyer Buckley and a French frigate were in the area where the rockets were fired.

Iranian and US forces have clashed in the Gulf in the past, especially during the Iran-Iraq war in the 1980s after the 1979 Islamic revolution.

Tehran and six world powers including the United States clinched an agreement in July that would curb Iran's nuclear program in return for lifting economic sanctions. – Reuters