Fifteen people were arrested for offenses such as resisting arrest, disorderly conduct and unlawful assembly, Tucson police Sgt. Pete Dugan said. Of those, 14 were released, and one was sent to Pima County jail. He said those who advanced on officers were arrested.
No officers or fans were injured in the unrest that lasted more than an hour.
"The majority of the crowd did not respond to the dispersal order and began throwing beer bottles, beer cans and firecrackers at the officers," Dugan said. "Several of the firecrackers rolled underneath a patrol vehicle that was deployed with the Mobile Field Force Units."
Dugan said crowds leaving bars and restaurants near campus filled University Boulevard after the game. They wouldn't leave despite urging through a PA system and social media declaring their gathering an unlawful assembly.
Police brought in cruisers and a unit of officers with batons, helmets and face masks to block the street when people started tossing beer bottles, cans and firecrackers, hitting police vehicles and endangering officers.
Officers fired pepper spray, pepper canisters and pepper balls, which disperse into the air when they hit, Dugan said. No tear gas was used despite some reports.
The disturbance lasted more than an hour until the streets began to empty around 10 p.m.
A witness, David Kitaeff, told The Associated Press that the incident started innocently with people taking photos, but then "people got in cops' faces." He said fans were throwing drink cans at officers, whom he saw marching down University Boulevard.
Police said no officers were injured and the only damage reported was a street sign that had been knocked over.
Officials said the names of those arrested individuals will be given to the Dean of Students to determine if any of them are currently enrolled at the university.
In a statement, Dean of Students Kendal Washington White called the disturbance "disappointing" and said it was not reflective of the culture of the University of Arizona and Tucson communities.
"Our basketball team had a great season and they exhibited exceptional class at every turn," White said. "They do not deserve the bad actions of these others."
White said all students who are found to have violated the school's code of conduct "will be held accountable."
Arizona lost 64-63 to Wisconsin in the West Region final Saturday in Anaheim, Calif.
In 2001, police arrested 17 people after Arizona lost to Duke in the national championship game. One student lost an eye after he was struck by a beanbag filled with lead birdshot fired by Tucson police.
Around 22 businesses suffered some damage from the 2001 unrest.