Police Searching For Lil Xan After He Hurls Mic, Kicks Man in Head on Video

Lil Xan's on cops' radar again ... we're told officers are looking for him after the rapper was seen on video punching and kicking a man at a show in Boston last week.

TMZ has obtained the clip ... which shows the rapper chatting up a few audience members at Royale, a nightclub, late Friday night/early Saturday morning -- and you can see him reach down and swing the mic at the man's face, physically knocking him to the ground.

Xan then spikes his microphone in the man's direction and -- when he finally gets back to his feet -- you see him kick the guy in the head before several people can separate the two.

The video doesn't appear to show the other man throwing a punch at the rapper ... and, it's unclear why this incident took place -- though another angle seems to show the guy flipping off LX.

Sources tell us security tried to grab Xan after the incident ... but, he took off before they could stop him -- and law enforcement sources tell us cops were called at just after 1:30 AM Saturday morning.

Our law enforcement sources say the call was for assault and battery ... with a witness telling them the attack was unprompted.

We're told the man refused medical attention at the scene. And, cops say they were also told Xan assaulted two other people while leaving the club.