Colorado Rockies Mascot Tackled During Game, Police Investigating

Police are on the hunt for a man who tackled the Colorado Rockies' mascot during a game on Monday ... believing he committed an assault with his surprising actions.

The incident happened at some point during the Rockies' game against the Cardinals at Coors Field ... when Dinger, Colorado's purple dinosaur cheerleader, hopped up on a dugout to fire up the crowd.

Suddenly, though, as Dinger was dancing around ... video shot by a fan in the stands shows a man jumped up and took the costumed character to the ground.

The moment initially seemed staged ... but, quickly, it was revealed it was anything but that.

The fan who shot the video suspected the man was inebriated ... writing in a caption on the video, "Boooo, drunk guy. [Love] you, Dinger!"

The Denver Police Dept. became aware of the incident shortly after it happened ... and confirmed to TMZ Sports it's now investigating it all as part of an assault case.

"We are working with our partners at the Colorado Rockies to identify the suspect," a DPD spokesperson told us on Thursday morning.

No arrests have been made yet ... but cops are urging anyone with information to reach out to Metro Denver Crime Stoppers.