Donald Trump just gushed about his friendship with a World Series champ during the Houston Astros visit to the White House ... while also dropping some humble brags about himself (duh).

"So, I know Justin. Justin's a friend of mine," Trump said while noting they play golf together.

"I'm a pretty long hitter," Trump bragged ... "[but] this guy, he is a monster!"

"And he said he's a -2 or a -3 handicap, but believe me, he's much better than that. He's about a +2 or +3. but we love playing and it was really great."

Trump also had some words for Jose Altuve ("you're taller than I thought!") and World Series MVP George Springer before reminding everyone he also played in high school!

He also assured the team the country's doing "fantastically well" under his leadership.