Dan Bilzerian -- Under Criminal Investigation for Face Kick

Dan Bilzerian is about to get a kick in the face himself ... because cops are investigating him for criminal battery ... TMZ has learned.

Model Vanessa Castano filed a police report after Bilzerian kicked her in the face Saturday night at LIV nightclub in Miami Beach.

If you haven't seen it already ... check it out. Bilzerian claims he kicked her because he was trying to help another woman on stage and Castano was blocking him ... not a great story for him.

When cops arrived at the club Bilzerian had already left, and Castano declined to file a report. But she had a change of heart and filled out the paperwork Sunday night.

Castano claims she suffered a laceration on her right eye and an abrasion on her lower back.