Iran apparently responded with attacks targeting Bahrain, Kuwait, Qatar and the United Arab Emirates.
The strait has become the key sticking point in any further negotiations between Iran and the US to find a permanent end to the war that began back on February 28.
About a fifth of all traded oil and natural gas passed through the strait before the war began.
Iran's grip on it during the war led to a global energy crisis, though oil prices have sharply dropped since wartime highs of $US120 ($A172) a barrel.
The US military's Central Command said it hit some 140 targets in the strikes, far more than the last two rounds, and went after missile and drone launch sites, ammunition dumps, communication equipment and other sites.
The attacks "degrade Iran's ability to attack civilian mariners and commercial vessels freely transiting the strait", it said.
The new crossfire in the Persian Gulf comes days after US President Donald Trump suggested an interim deal in the Iran war was "over".
US Defense Secretary Pete Hegseth wrote online: "Iran made a poor choice. Now they pay."
Mohammad Bagher Qalibaf, the speaker of Iran's parliament and a main negotiator, responded.
"The era of one-sided deals is OVER," he wrote on X. "We told you: keep your word or pay the price. Reality is knocking."
Meanwhile, missile alerts sounded in Bahrain on Sunday, an island kingdom in the Persian Gulf home to the US Navy's 5th Fleet. Kuwait's military said it was intercepting incoming fire.
It wasn't immediately clear what locations were under attack in the UAE, which so far hadn't been targeted in the latest round of The United Arab Emirates warned the public on Sunday of an incoming missile and drone attack as explosions could be heard in nearby Qatar.
A missile alert sounded in Qatar shortly after the blasts. Qatar's military said in a statement it intercepted the incoming Iranian fire.
The latest attack on the Emirates, home to Abu Dhabi and Dubai, came in May when a drone sparked a fire on the edge of the country's sole nuclear power plant.
Iran also made a series of claims about attacks elsewhere that were not immediately confirmed.
In the Strait of Hormuz attack, a Cyprus-flagged container ship was hit by Iran and suffered "significant engineroom damage" and a civilian crew member is missing, US Central Command said.
The United Kingdom Maritime Trade Operations centre, overseen by the British military, said the ship had been travelling in a route hugging the shoreline of Oman.
That's been the way ships have navigated the Persian Gulf while avoiding Iranian territorial waters. The ship's crew abandoned the vessel as it was ablaze, the centre said.
Iran's paramilitary Revolutionary Guard said multiple vessels "disregarded our warnings and instructions to correct their course and proceed along the approved route".
One of them "was struck by a warning shot and brought to a stop".
Iran said that the strait would remain closed "until further notice" and said it would consider targeting "additional enemy bases in the region" if it faced more attacks.
Iranian state media reported US strikes across a swathe of southern provinces, including Bushehr, Hormozgan, Khuzestan and Sistan and Baluchestan provinces. It offered no immediate damage or casualty figures from the strikes.
The latest violence followed Iran and Oman's foreign ministers meeting on Saturday to discuss the strait, after days of Iranian attacks on ships and US retaliation that dealt a blow to the interim deal to end the war.
Oman said it and Iran agreed to keep talking about the Strait of Hormuz "at the technical and political levels".
However, Iran offered no statement about the strait being open to all - something sought by the Trump administration.
Iran's new supreme leader, still unseen since the war began, also vowed in his first statement since the funeral of his father, Ayatollah Ali Khamenei, that Iranians would avenge his killing in the war's opening strikes on February. 28.
Such revenge "is the will of our nation and must certainly be carried out", Supreme Leader Ayatollah Mojtaba Khamenei said in a statement carried on state televisions.
with Reuters
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