A message sent to ships in the Persian Gulf says that the strait is closed and that ships need permission from Iran's Revolutionary Guard to pass.
"Any ships attempting to go to sea will be attacked and destroyed," the warning reads, according to the BBC.
One of the demands from US President Donald Trump for a ceasefire was that Iran open the Strait of Hormuz. This was granted and at noon on Wednesday two ships passed through the important shipping lane for oil trade.
But Iranian state media report that the strait is now closed, saying this was justified by Israel's massive attack on Lebanon on Wednesday. Over 250 people are said to have been killed in the attacks.
According to Pakistan, which brokered the ceasefire between the US and Iran, Lebanon is covered by the agreement. However, Israel and the US claim that this is not the case.
