"I'm gonna f****** knock his teeth in!"

Uhhhh ... that's "Platinum" Mike Perry promising to go all dental on Jake Paul, telling us he's gonna beat The Problem Child's ass!

32-year-old Perry joined Babcock on the "TMZ Sports" TV show (airs nightly on FS1) ... and two things are clear ahead of his July 20 boxing match with 27-year-old Paul -- he's fired up, and there's a beef between 'em. A lot of it.

"F*** Jake, bro," Perry said ... "We've never been friends. He's never been cool with me, he wanted to beat me up, and he's a sneaky little snake, and I'm gonna f****** knock the teeth out of his mouth. F*** him. F*** you, Jake. I'll beat your ass, bitch."

Of course, Jake was initially scheduled to fight Mike Tyson on the 20th, but after Iron Mike suffered a mid-air medical emergency on his flight from Miami to Los Angeles, the fight was pushed to November.

Shortly after ... the fight against Perry came together.

After departing from the UFC, Perry signed with Bare Knuckle Fighting Championship -- where he's currently BKFC's biggest star, sporting a 5-0 record, with wins over Luke Rockhold and Michael "Venom" Page, among others.

Mike previously told us he wanted to fight Jake in bare knuckle, but says that was a non-starter with Paul, who he says wanted no part of that setup.

Still, MP has an idea.

"Jake can take his gloves off and I'll put the gloves on, and I'll still whoop his ass," Paul said. "He can fight me bare-knuckle, and I'll punch him with 10-ounce gloves."

Perry and Paul do have some history ... they briefly trained together a few years back, though Mike says he doesn't think he can gleam a whole lot from the sparring sesh. Still, it was enough for Mike to know that Jake's right could be a potential problem.

"I know his right hand. I understood it back then when he hit me with it; that's his little thing, and I get it. I got a couple of shots that I'm really good at, too. We're both in for a battle. It's gonna be a fight, and it's gonna be a test of wills."

Perry, at the end of the day, predicts he will finish Paul off by the seventh round.