Gunplay Says He Wants to KILL 50 Cent!! -- Video Inside

Gunplay says he absolutely DID NOT fire a gun at the BET Awards ... but claims he DID beat up a member of 50 Cent's entourage ... and says he wants to "kill" everyone in the G-Unit crew. Gunplay -- a rapper who's signed to Def Jam -- just called in to TMZ Live to talk about the madness at the BET Awards in Atlanta on Saturday ... where multiple fights broke out behind the scenes.

Gunplay tells us ... he "had to fight off five dudes" who he believes were members of 50 Cent's camp.

Gunplay says things got violent with 50's group because, "I never liked them and always wanted to kick his ass ... and I finally got the opportunity."

The rapper says 50 Cent WAS involved in the action ... but was "hiding behind security." Gunplay says he was trying to "break his f*ckin' neck."

Gunplay says he did manage to beat down one of the guys in 50's entourage -- "kicked one of their fat-asses ... kicked them off in the dirt." Gunplay says cops then rushed in and sprayed him with mase.

Gunplay -- who's friends with Rick Ross -- says his fight had nothing to do with Rick's altercation with Young Jeezy's crew at the BET Awards ... but explains, "We just goin' at it with everybody ... let's go kill 'em all."

Doesn't sound like he was joking ... Gunplay told us, "If you're playin' with me, you're playin' with fire ... might get gunned down, ya never know."