Captain Thulani Zwane said about 150 students protested on the institution’s Howard College campus on Thursday.
He said the public order policing unit had been deployed and that the campus was quiet in the afternoon.
University spokesman Lesiba Seshoka said two car belonging to staff were damaged by some 600 protesting students.
Students marched on the Umbilo police station to demand the release of fellow students. Police could not immediately confirm this.
Seshoka said the students had violated a high court order prohibiting protests. Police had used teargas and rubber bullets to disperse them.
He said management met student representatives to deal with issues, primarily around student funding, student housing, and fees.
Friday was the last day for students to register.
“All students are reminded that the final high court interdict prohibiting mass action and unlawful protests remains in place.”
About 100 students held a peaceful protest at the university’s medical campus, Seshoka said.