Dana White: "Conor McGregor Would Beat Mayweather's Ass!!"

Conor McGregor's got some major support from his boss -- 'cause UFC honcho Dana White tells TMZ Sports he's 100% confident Conor would CRUSH Floyd Mayweather in a street fight.
Dana was out in NYC today ... when we asked about McGregor's fight prediction -- that he would WRECK Floyd in less than 30 seconds.
White doubled down even harder -- saying EVERY SINGLE FIGHTER on the UFC roster could take it to Floyd ... 'cause he's only skilled in 1 simple fighting style.