Birdman -- I'm Not Involved in Plot to Shoot Lil Wayne

Birdman's finally breaking his silence on the Lil Wayne shooting, and despite police docs tying him and Young Thug to the suspect -- he's denying ANY involvement in a murder-for-hire plot.

Sources close to Wayne and Birdman confirm to TMZ what police docs insinuated ... that Birdman got a phone call on April 26, shortly after the bus was shot up in Atlanta. As we reported, police knew the call was placed between 2 phones registered to Birdman.

We're told the call came from someone in Wayne's camp who was understandably pissed, and anxious to tell Birdman what went down shortly before the shooting -- that Jimmy Carlton Winfrey had been kicked out of a club for harassing Wayne.

Winfrey was eventually arrested and charged with the shooting.

Our sources say Birdman assured Wayne he was not involved in any way, and vowed to help figure out who was behind it.

We're also told the phones being registered to Birdman is not surprising, because they're company phones and everyone using them -- Wayne's people, Birdman, and even Winfrey -- is associated with Cash Money or Young Money.