The U.S. strikes followed attacks on vessels in the strait, the U.S. said.
President Donald Trump announced "major combat operations" against Iran on Feb. 28, with massive joint U.S.-Israeli strikes targeting military, government and infrastructure sites.
Delegations from the U.S. and Iran entered negotiations last month aimed at a war-ending deal based on a memorandum of understanding signed by both countries.
The U.S. and Iran nonetheless exchanged limited strikes in late June despite the signing of the memorandum and amid the continuation of peace talks.
The Kuwait Army said in a post to X on Wednesday morning that its air defenses were "confronting hostile missile and drone attacks."
In Bahrain, meanwhile, the Interior Ministry confirmed in posts to X that air defense sirens were being sounded.
The Iranian military on Wednesday claimed to have attacked U.S. military bases in both nations.
Iran's military said it launched on Wednesday attacks targeting 85 U.S. military sites in Kuwait and Bahrain, saying they were retaliatory strikes following a wave of U.S. airstrikes on Iranian targets.
The Islamic Revolutionary Guard Corps said in a statement that it targeted Bandar Salman, the Fifth Naval District in Bahrain and Ali Al-Salem Air Base in Kuwait.
Bahrain's Interior Ministry said air raid sirens were activated, adding that all "citizens and residents are urged to remain calm and head to the nearest safe place."
Iran also claimed to have destroyed a drone "that intended to interfere with the operation."
-ABC News' Joe Simonetti
Lead Iranian negotiator Mohammad Bagher Ghalibaf, accused the U.S. of "major MOU violations" after U.S. airstrikes on Tuesday.
In a statement on social media, Ghalibaf, who also serves as Iran's Parliament speaker, listed a number of items he claimed as violations of the memorandum of understanding between Iran and the U.S. that temporarily paused hostilities.
Among them: "Violating Iranian adjustments in the Strait"; "Persistent threats of further strikes"; and "Reinstating oil sanctions."
The post ended: "The era of bullying and extortion is over. It leads nowhere. We don’t fold."
The U.S. said it carried out the retaliatory airstrikes in response to Iranian attacks on commercial vessels traveling through the Strait of Hormuz.
U.S. forces hit over 80 targets overnight in a new round of airstrikes that came as an "immediate response" to Iran's attacks on three commercial vessels transiting the Strait of Hormuz, U.S. Central Command said.
"U.S. forces struck Iranian air defense systems, command and control networks, coastal radar sites, anti-ship missile capabilities, and more than 60 Islamic Revolutionary Guard Corps small boats in and near the strait to degrade Iran’s ability to continue attacking international commerce flowing through the international trade corridor," CENTCOM said in a social media post.
CENTCOM described them as "offensive strikes" -- in contrast to strikes last month that the U.S. military characterized as "self-defense strikes."
CENTCOM said the recent strikes targeting commercial tankers in the strait amounted to "unwarranted aggression" and a clear and dangerous violation of the ceasefire and undermines freedom of navigation.
"CENTCOM forces remain postured and prepared to hold Iran accountable when the agreement is not adhered to or obeyed," the U.S. statement said.
