Diddy, 45, whose real name is Sean Combs, was arrested at UCLA's Acosta Athletic Training Complex on suspicion of assault with a deadly
weapon shortly after 12:30, according to a statement from campus police.
The deadly weapon was a kettlebell, which is used by athletes in weight training.
No one was seriously injured and campus police are investigating. Officials did not identify the victim of the assault, or say what led to it.
Combs' son Justin Combs is a redshirt junior defensive back on the UCLA football team, which has been working out on campus. He has played in just a handful of games in his three years with the team.
Football coach Jim Mora thanked his staff in the statement for their professionalism in handling the situation.
"This is an unfortunate incident for all parties involved," Mora said. "While UCPD continues to review this matter, we will let the legal process run its course and refrain from further comment at this time."
Combs' representatives did not immediately respond to requests for details or comment.
The arrest was first reported by TMZ.