Adam 'Pacman' Jones -- Pleads NOT GUILTY to Woman Punching

Cincinnati Bengals star Pacman Jones just pleaded NOT GUILTY to assault ... after allegedly socking a woman in the face outside of a Cincinnati nightclub last week.

Jones insists he was "protecting himself" during the June 5 incident ... after a woman appeared to pour a drink on the 29-year-old cornerback outside of a Cincinnati nightclub.

Just yesterday, surveillance video of the incident surfaced ... appearing to show the woman lunging toward Jones with a drink in her hand. The person believed to be Jones reacts by clocking her in the face ... hard.

The woman pressed assault charges ... police characterized her injuries as minor ... and just yesterday, Pac turned himself in to police.

Now, with Jones entering a not guilty plea ... it's clear he's digging in for a legal war.