The Chicago Bears defensive lineman has been handed a 2-game ban by NFL commish Roger Goodell on Friday ... but we're told it is NOT related to an alleged domestic violence incident in October.

TMZ Sports broke the story ... a woman claims 26-year-old Edwards got violent with her in a North Carolina hotel room on Oct. 17 (the day before playing against the Panthers) ... after she turned down his sexual advances.

The woman claims she was pregnant at the time of the incident ... and required medical attention for injuries sustained during the alleged attack.

Edwards, though, has STRONGLY denied any wrongdoing ... claiming he was the victim and the woman was the aggressor.

While that incident remains under investigation, we're told Edwards' punishment Friday is due to a violation of the league's performance-enhancing substance policy ... resulting in the 2-game ban.

Edwards showed serious promise in 15 games for the Bears this season ... racking up 4 sacks in 15 games.