In the latest blow to the fragile ceasefire agreement, the Islamic Revolutionary Guard Corps said it had carried out a joint missile and drone operation against key US military sites in Bandar Salman, Bahrain's Fifth Naval District and Ali Al Salem Air Base in Kuwait, and shot down a US MQ9 drone attempting to interfere in the operation.
Air raid sirens sounded in Bahrain and Kuwait on Wednesday, officials said.
The Kuwaiti army said air defences were confronting "hostile" missile and drone attacks.
The US earlier unleashed "over 80" fresh military strikes and revoked a licence allowing Iran to sell oil in response to attacks on three tankers in the strait.
The US Central Command said more than 60 small boats of the Islamic Revolutionary Guard Corps were among the targets hit, in a bid to impose a heavy cost on Iran for strikes on shipping in violation of the ceasefire.
"The unwarranted aggression by Iranian forces is a clear and dangerous violation of the ceasefire and undermines freedom of navigation," CENTCOM said on X.
Iran's top joint military command, Khatam al-Anbiya Central Headquarters, condemned the US strikes as a "blatant act of aggression", threatened a "crushing response" and warned Tehran would not allow US interference in the management of the strait.
A top Iranian negotiator, parliament speaker Mohammad Baqer Qalibaf, accused the US of breaching the ceasefire agreement.
He cited not only the latest US military strikes, but renewed oil sanctions, violations of Iranian "adjustments" in the Strait of Hormuz and Israeli attacks against Lebanon.
"The era of bullying and extortion is over," Qalibaf said in a post on X.
"We don't fold."
Iranian media earlier reported explosions in Iran's main oil hub of Kharg Island, on Qeshm Island and in the southern port cities of Sirik and Bandar Abbas.
Iran's Press TV reported several blasts were heard in southern Kharg Island. CENTCOM made no mention of Kharg Island, from which Iran exports 90 per cent of its crude oil.
A US official told Reuters that strikes targeted Iranian air defence systems, coastal surveillance systems, surface-to-air missiles, anti-ship cruise missiles and drone launch sites.
Several people were injured by shrapnel from an "enemy projectile" that hit a commercial pier in Sirik, according to an Iranian state TV reporter. The reports said strikes also hit fishing piers in Sirik and in Bandar Abbas.
The incidents were the latest threat to the fragile ceasefire agreement the US and Iran struck last month, pausing the conflict that started with US and Israeli strikes across the Islamic Republic.
In a potentially major blow to that agreement, Washington moved on Tuesday to withdraw a key concession that had allowed Iran to sell oil on international markets.
Oil prices rose more than three per cent after the US announced the move.
A US official said earlier that negotiators continued to work in good faith toward a final agreement with Iran. But control of the strait has given Tehran immense leverage, effectively allowing it to force a stalemate with the world's most powerful military.
Analysts say Tehran uses attacks on ships to underscore that leverage as it negotiates a long-term peace deal with the US Under the interim US-Iran agreement, the US Treasury issued a June 22 general licence to allow the sale of crude oil and petrochemical and petroleum products of Iranian origin through August 21.
In revoking that licence on Tuesday, it gave Iran until July 17 to wind down any transactions.
Iran's foreign ministry condemned the move as a breach of the framework agreement to end the war and said Washington would bear responsibility for the consequences.
The ministry said Iran would take any measure necessary to safeguard its interests and national security.
While Tehran denied responsibility for the latest strikes on ships in the strait, Qatar blamed Iran for attacking the vessels, including the huge Qatari liquefied natural gas tanker, the Al Rekayyat, which reported being struck by a drone that caused a fire in its engine room. The crew were safe and being evacuated.
A Saudi-flagged crude oil tanker, believed to be the supertanker Wedyan, was also damaged off Oman, maritime security sources said. The cause was not immediately clear.
Iran's foreign ministry said Qatar's accusations were perplexing and that Tehran was diligently fulfilling its commitments. Even so, it said commercial vessels faced risks for using routes not coordinated with Iran.
Iran's clerical rulers aim to install a permanent system to collect fees in what would amount to a huge shift of the balance of power in a region where Washington has long acted as guarantor of security.
US President Donald Trump has repeatedly threatened to resume bombing unless Iran agrees to "make a deal".
