"I'm not trying to kill nobody. My whole thing is that I'm tryna break some faces, so come October 4, I'm going straight to this dude and I'm breaking his f***ing face."

That's 24-year-old Teofimo Lopez vocalizing his violent intentions ... telling TMZ Sports 28-year-old George Kambosos Jr. confronted his family in South Florida, while Lopez was battling COVID-19, and that's out of bounds -- so he must pay.

"From what I heard, because I wasn't in Miami, he was acting all big and bad and tough, I was over here having COVID and I was dying here in Vegas," Lopez says.

"I heard that he had screamed at my whole team, my whole family and cursin' at them while I wasn't there. He wouldn't have done that had I been there. So, it comes to show, like, that's just something that you don't do, especially with my mom, ya know?"

FYI, Teofimo (16-0) and George (19-0) are both undefeated. Lopez is the unified lightweight champion.

The bad blood originates from earlier in the summer ... when Lopez was forced to pull out of their originally scheduled June 19 fight because he caught COVID.

Kambosos was pissed, believing he sacrificed time with his family to train for the fight, but it never happened.

Things were said ... and Teofimo believes George took the trash talk to a place it shouldn't go -- families.

"This is the fight game, but when you take it to that next level, and I think everybody understands that family -- you don't ever cross that," Lopez says.

"I think that's where it comes down to and I just look at it now where I'm at the point where look, he has kids of his own so I'm praying for his health afterwards, but in the meantime, nah man, I'm trying to break necks."