US President Donald Trump on Saturday gave Iran 48 hours to reopen the Strait of Hormuz to shipping or face the destruction of its energy infrastructure, as Tehran launched its most destructive attack yet on Israel.

The ultimatum, made just a day after the US leader said he was considering "winding down" military operations after three weeks of war, came as the key oil passage remained effectively closed and thousands more American Marines headed to the Middle East.

Trump wrote on Truth Social that the US would "hit and obliterate" Iranian power plants — "starting with the biggest one first" — if Tehran did not fully reopen the strait within 48 hours.

Iran's Foreign Minister Abbas Araghchi said Tehran had imposed restrictions only on vessels from countries involved in attacks against Iran, and would assist others that stayed out of the conflict.

In response to Trump's threat, Iran's army said it will target energy, desalination infrastructure "belonging to the US and the regime in the region," according to the Fars news agency.

Trump's ultimatum landed hours after two Iranian missiles struck southern Israel, injuring more than 100 people in the most destructive attack since the war began.

Israeli Prime Minister Benjamin Netanyahu vowed to retaliate "on all fronts". (AFP)


Edited by Tony Sabine