Washington DC - President Donald Trump said Saturday that Iran would "no longer exist" if the United States is "forced" to resume the war, as he accused Tehran of violating a ceasefire.

The threat came after US forces said they struck "multiple" Iranian targets Saturday in another tit-for-tat response to attacks on shipping in the vital Strait of Hormuz.

"United States aircraft just struck Iranian missile and drone storage locations, and coastal radar sites, for violating the Cease Fire Agreement, AGAIN!" Trump wrote on Truth Social.

"There may come a point when we are no longer able to be reasonable, and will be forced to militarily complete the job that we very successfully started. If that happens, the Islamic Republic of Iran will no longer exist!" Trump wrote.

The clashes brought new tension to the negotiating process meant to end a war launched by the US and Israel at the end of February.

They also underlined the risks still facing one of the world's most important sea lanes for oil and other commodities.

US Central Command said Saturday's strikes were in response to an Iranian drone attack on the Panama-flagged oil tanker "Kiku," which was carrying some two million barrels of crude.

The US military said the latest response targeted "surveillance infrastructure, communication systems, air defense sites, drone storage facilities, and minelayer capabilities."

Iranian media reported several explosions in the Sirik and Qeshm areas of southern Iran.

On Friday, the US also conducted strikes that it said were in response to another Iranian attack on a ship, the "Ever Lovely."

Iran said Saturday it had hit US targets in the Gulf in its own retaliation. Bahrain said it was targeted by several Iranian drones early on Saturday and accused Tehran of "sabotaging peace efforts."

Iran's Revolutionary Guards said, "If the aggression is repeated, our response will be broader."

Israel, meanwhile, launched strikes in Lebanon, and Hezbollah's leader Naim Qassem rejected a deal to end that conflict, which has also threatened to derail the wider US-Iran peace effort.

Iran called "these brutal attacks... a blatant violation" of the interim truce deal.