US Central Command said aircraft struck missile and drone storage locations and coastal radar sites. CNN, citing an unnamed US official, reported the US operation had concluded.
Centcom justified the strikes as a "powerful response" to Iran's attack on the Singapore-flagged vessel M/V Ever Lovely as it was exiting the Strait of Hormuz.
Cencom denounced the "unwarranted aggression against commercial shipping by Iranian forces" as a clear violation of the ceasefire.
Iranian media reported a projectile struck an area around a pier in Sirik, a city on the shores of the strategic waterway.
US President Donald Trump blamed Iran for the ship attack near Oman.
Two US officials had told Reuters on condition of anonymity that Iran had fired on the ship.
"I don't like the fact that they took a shot yesterday, actually four of them," Trump said at the White House shortly before the US struck back.
When asked why there would be strikes when Trump has insisted talks with Tehran are going well, Trump said: "They're a little bit different."
He then abruptly cut off questions and reporters were ushered out of his office.
Iran had earlier expressed anger at what it said was an "interventionist, irresponsible and provocative" statement by the United States and six Gulf states that rejected its assertion that it could charge tolls on vessels transiting the strait.
"Safe passage through the Strait of Hormuz cannot be guaranteed under ambiguous arrangements, parallel routes or decision-making that does not take Iran's role as a coastal state into account," Iranian Deputy Foreign Minister Kazem Gharibabadi said on X.
Bloomberg News said Oman, which lies on the opposite side of the strait from Iran, had told allies ships going through Hormuz may have to pay.
Reuters could not immediately confirm the report.
The foreign minister of fellow Gulf state the United Arab Emirates held his first announced phone call with his Iranian counterpart since the start of the conflict, UAE state news agency WAM said, underlining efforts to overcome tensions.
It said Sheikh Abdullah bin Zayed underlined the need to ensure freedom of navigation through the strait, where shipping had picked up pace before a new slowdown after the ship attack.
Iranian state TV said three foreign tankers attempting what it called an "unauthorised passage" of the strait were turned back after a warning from the Islamic Revolutionary Guard Corps.
Elsewhere there were signs of progress as Israel and Lebanon signed an agreement to end the fighting between Israel and Iran-backed Hezbollah.
Both sides framed the deal as an initial step that calls for Hezbollah to disarm and Israel to withdraw troops from Lebanon, but it was not clear how it would be enforced. Hezbollah said it would not co-operate.
Secretary of State Marco Rubio joined Israel and Lebanon's ambassadors in Washington on Friday to announce the framework agreement that was described as a first step toward peace following months of conflict.
The agreement was signed in front of Rubio by Yechiel Leiter, the Israeli ambassador to the United States, and Nada Hamadeh Moawad, the Lebanese ambassador to the United States.
Leiter said the final destination of the framework is peace between the two countries.
"Our language is we want to embrace Lebanon," he said.
"Our language is we want to get in our car in Tel Aviv and take a drive up to Beirut, and we want Beirut to come down and take a drive to Tel Aviv. That's where we're going. That's where we want to go."
with DPA and EFE
