Stephen Jackson is FURIOUS at Donald Trump for mentioning George Floyd's name at the White House on Friday ... and he's now warning POTUS not to let it happen again!
"Hey, this message is for Donald Trump," Jackson said in a heated video statement ... "Do not speak on my brother's name."
"I'm making you a promise, you will not be in the White House come November. You will not be reelected, I'm telling you now."
Earlier in the day, Trump spoke with the media from the Rose Garden and said he hoped George is looking down right now -- "This is a great thing that's happening for our country. It's a great day for him. It's a great day for everybody ... in terms of equality."
Enter Jackson ... who knew Floyd for years -- and he's pissed.
"You see how the whole world stood together? Arm to arm, race to race, everybody standing for love? 50 states, 18 countries. That's what me and my brother Floyd did. So we coming to get you out the White House."
Clearly, Jackson feels the next course of action is to mobilize the protesters into voters come November.