Port Elizabeth - Nelson Mandela University (NMU) students blocked the entrances at the South and North Campus on Thursday, the second day of a protest mainly over funding and registration.
The students are angry that some of them have been barred from registering over non-payment of fees, even though the government has pledged free tertiary education for learners from poor households.
The NMU said lectures on Thursday were postponed until further notice, urging students and staff to continue with their work off campus.
University spokesperson Zandile Mbabela said the institution would enforce an existing interdict against protesting students disrupting activities on campus.
Mbabela said physical disruptions would not be tolerated and NMU had a duty to protect the rights of staff, students and all other stakeholders.