DUBAI, United Arab Emirates - The United States on Wednesday accused Iran of launching a "highly provocative" rocket test last week near its warships and commercial traffic passing through the Strait of Hormuz, exposing how tensions between the two countries could escalate even after a landmark nuclear deal.

The strategic Persian Gulf waterway, which sees nearly a third of all oil traded by sea pass through it, has been the scene of past confrontations between America and Iran, including a one-day naval battle in 1988.

But Saturday's incident brought no immediate response from Iranian officials or media, while French authorities downplayed its danger.

Military vessels taking part in the war against the Islamic State in Iraq and Syria also pass through the narrow waterway between Iran and Oman. On Saturday, the USS Harry S. Truman aircraft carrier, the USS Bulkeley destroyer and a French frigate, the FS Provence, were passing through it, said Cmdr. Kyle Raines, a U.S. Central Command spokesman.

As they passed, Iranian Revolutionary Guard vessels, hailing other ships in the strait over maritime radio, announced they'd be carrying out a live fire exercise, Raines said in a statement.

After 23 minutes, the Iranian boats fired "several unguided rockets" about 1,500 yards from the warships and commercial traffic, he said.

While the rockets weren't fired in the direction of any ships, Raines said Iran's "actions were highly provocative."

"Firing weapons so close to passing coalition ships and commercial traffic within an internationally recognized maritime traffic lane is unsafe, unprofessional and inconsistent with international maritime law," he said.

A French military official, speaking on condition of anonymity as he was not authorized to be publicly named, confirmed the rocket fire took place Saturday. However, the official said the French military did not consider it to be a threatening event as the rocket fire clearly wasn't directed toward the Western fleet.

The French frigate is now escorting the French aircraft carrier Charles de Gaulle, which is launching airstrikes against the Islamic State, the official said.

NBC News first reported news of the Iranian rocket fire.

The Strait of Hormuz is only about 21 miles wide at its narrowest point. Ships traversing the chokepoint have even less room to maneuver. The shipping lane in either direction is only 2 miles wide, with a 2-mile buffer zone between them.

The U.S. Navy's Fifth Fleet is based in nearby Bahrain, on the southern coast of the Persian Gulf. It conducts antipiracy patrols in the greater gulf and serves as a regional counterbalance to Iran.