Floyd Mayweather Sr. Says He'll Beat a White Supremacist's Ass

He's 64 years old ... but if a white supremacist steps to Floyd Mayweather Sr., the boxing veteran says he won't hesitate to beat that ass.

Floyd Sr. was flying back to Vegas after a whirlwind trip to L.A. when we asked if he was worried about his own safety with the rise of white supremacist rallies all over the country.

"I'm telling you right now ... if it comes to the point, where I gotta take care of my business, I'm gonna take care of my business," Floyd said.

"Believe me, I'm gonna clean it up good."

Floyd was 28-6-1 as a pro fighter back in the day -- and helps train his son on a daily basis out in Vegas.