'Sugar' Shane Mosley Investigated for Alleged Domestic Violence Incident (UPDATE)

Jan. 12th -- Shane's girlfriend tells TMZ Sports she is NOT planning on pressing charges and insists the boxer did not attack her.

Here's her explanation of the incident -- "We were fighting about my birthday, and he was moving me out of his way so he could leave and end the argument. AS he pushed me aside I fell over a toy that was in the hallway where we were. I had no bruise or injury at all."

10:50 AM PT -- Shane tells TMZ Sports he did NOTHING wrong. He says the two had a verbal argument and she "tripped."

He adds, "I didn't push her."

"She tripped and she didn't have any injuries. We were just yelling."

Boxing star "Sugar" Shane Mosley is being investigated for an alleged domestic violence incident after his girlfriend told police he roughed her up this weekend ... TMZ Sports has learned.

Law enforcement sources confirm cops were called to an L.A. home just after midnight on Sunday morning. When they arrived to the scene, 45-year-old Shane was not there.

The accuser told cops she and Shane had been arguing earlier in the night -- but things escalated and Shane pushed her.

The woman claimed she suffered minor injuries and complained of pain. We're told cops are investigating the incident.