Donald Trump might as well be the next recipient of the UFC's "BMF" belt ... 'cause Dana White gushed over No. 45's handling of this weekend's assassination attempt -- calling his close friend the "ultimate American badass."

The UFC honcho joined "The Pat McAfee Show" on Monday to share his reaction to Saturday's rally shooting in Butler, PA ... and he said he was "literally blown away" by how The Donald responded after nearly losing his life at the hands of Thomas Matthew Crooks.

"This guy is almost 80 years old," White said minutes ago. "The guy tried to blow his head off. And to have the reaction that he did when he got up, this guy has been a friend of mine for 25 years, one of the greatest human beings I've ever met. He's an unbelievable friend, and he's forever now the ultimate American badass."

White went on to explain it doesn't matter what people think of Trump -- it's now "undebatable" how tough he is ... and he proved that on Saturday.

White revealed he had a 30-minute conversation with Trump shortly after he was released from the hospital ... and also debunked reports the former President was initially planning to attend UFC Fight Night in Denver later that evening.

White will undoubtedly continue to sing Trump's praises later this week ... as he's slated to introduce him at the Republican National Convention.