Jackson's then-girlfriend Supriya Harris claims the NFL star got physical during an "argument" in March 2009 ... this according to a complaint filed with the Las Vegas Police Department.
In her complaint, Harris says, "Steven became enraged and pushed me to the ground, repeatedly."
Harris also claims Jackson, "forcibly grabbed my arm and flung me against the door. I was crying and trying to protect my stomach from the blows, as I was 9 mos pregnant."
In the complaint, Harris claims Jackson "continued to shove me against the door until his nephew ... interceded and yelled, 'uncle, she has a baby, stop.'"
Harris claims she was "bleeding heavily" from wounds she received after she was smashed into a door handle.
Harris says Jackson took her to a nearby hospital -- but instructed her to lie and tell doctors that she was injured from a fall in the shower.