A video grab shows an Iranian Navy vessel near a US ship.
The Pentagon said the Iranian Revolutionary Guard Corps boats "repeatedly crossed the bows and sterns of the US vessels at extremely close range and high speeds," coming at one point within 10 yards (nine metres) of the bow of one.
At the time the US Navy and Coast Guard ships were conducting operations in international waters in the northern Gulf with Apache attack helicopters, the US Navy said in a statement.
The much smaller speedboat-like IRGC Navy vessels ignored warnings from the US ships for about one hour, before finally responding to radio communications and then leaving, the US side said.
"The IRGCN's dangerous and provocative actions increased the risk of miscalculation and collision," the US said, adding they violated maritime customs and laws.
Pompeo discussed Iran and maritime security with Gulf Arab allies during a trip to the region after President Donald Trump called off a military strike to retaliate for Tehran's downing of a US drone.
President Donald Trump has blamed Iran for attacks on oil tankers near the strategic Strait of Hormuz, but he also held out hope that implicit US threats to use force will yield talks with the Islamic Republic as the Pentagon
The video, published on Thursday on the US Central Command's website, purports to show the crew of an Iranian patrol boat removing an object from the hull of a vessel whose markings appear to match archive footage and pictures of the Japanese-owned tanker Kokuka Courageous.
Polls opened on Saturday in Malaysia’s eastern Sabah state in a vote seen as a referendum for embattled Prime Minister Muhyiddin Yassin’s 7-month-old unelected government.
New Zealand reported two new coronavirus cases on Saturday -- one in managed isolation and the other detected during contact tracing, taking the overall tally to 1,475, according to the Ministry of Health.
Togolese Prime Minister Komi Selom Klassou and his government tendered their resignation on Friday, the presidency said in a statement, congratulating the Cabinet for its work in office.
South Korea said on Saturday it will request North Korea to further investigate the killing of a South Korean government official who was shot by North Korean troops after being found adrift near the rivals’ disputed sea boundary while apparently trying to defect.