Donald Trump Tells Reporter She 'Knows Nothing' After Question About Iran

President Donald Trump berated a reporter on the White House Lawn Saturday ... telling her she doesn't know a darn thing about Iran.

POTUS spoke to several reporters waiting for him outside the White House round 5 PM ET today ... and, one asked a question about why the Strait of Hormuz isn't open yet.

Check out the clip ... the prez is clearly unhappy about it -- and, he tells her "You know nothing" before asking which outlet she represents.

She says NBC ... which he calls "fake news" -- before claiming the United States has completely defeated the Iranian navy, sinking more than 150 ships to the bottom of the sea.

Trump goes on to say they have no radar, no air force and their Ayatollah Ali Khamenei is dead ... a complete and total victory for the USA.

To be fair ... the Strait of Hormuz still isn't open -- with reports circulating that Iran can't find the mines it put in the water to close it.

This obviously isn't the first time Trump has been vicious with a reporter ... though it's certainly not as nasty as when he called a female reporter a "piggy" on Air Force One.

The president's comment about Iran came while U.S. and Iranian officials in Pakistan discuss a ceasefire to end the conflict which began at the end of February.

Vice President J.D. Vance is leading the American delegation ... and NBC News reported around 4:30 PM PT the talks have reached 15 straight hours in Islamabad.