White, a Boston Celtics star and a Univ. of Colorado alum, attended the Buffaloes' big rivalry matchup with Colorado State over the weekend at Canvas Stadium in Fort Collins in some CU swag ... and, initially, it looked like he was enjoying the game without issue.

But, one witness in attendance tells us during the second quarter ... the hooper got into a bit of a verbal spat with some Rams fans as Deion Sanders and Co. began handling business on the field.

In the third quarter -- as it became clear White's Buffs were likely going to win -- the apparent arguing turned violent ... as you can see in our video, a man in a CSU hat and a Utah shirt swung his arm into the side of White's head.

The blow connected so hard -- it knocked the hat right off White's dome ... and a huge skirmish then ensued.

Multiple people raced in ... and while White was pulled out of the mix quickly -- nearly a dozen people pushed, shoved and put each other in headlocks for several moments.

Thankfully, law enforcement arrived before things escalated further ... and the scuffle dispersed. We're told White could be seen walking away from the area by heading up some nearby stairs.

We've reached out to White's camp for further information on the matter, but so far, we've yet to hear back.

As for cops, they tell us there was no police report filed regarding the encounter.