Nicole Cannizzaro filed the lawsuit in L.A. County Superior Court, claiming Dourdan launched an unprovoked attack on her while she was shopping at a Whole Foods last November with the actor's child.

According to the lawsuit, Nicole immediately hopped a ride to Gary's apartment nearby to grab her stuff -- and Gary arrived soon after, continuing his attack ... punching her in the face and dragging her across the floor.

Nicole claims she tried to call 911, but Gary's roommate stopped her. A neighbor eventually called the police and Gary was arrested.

Gary has since been charged with felony assault and battery -- and a judge issued a restraining order against him on Nicole's behalf.

Nicole is now suing Gary for assault, battery, and intentional infliction of emotional distress. She is seeking unspecified damages, totaling at least $25,000.