Police made a rare entrance into the grounds of the National Technical University of Athens (NTUA) on Wednesday morning.
No official reason was given for the operation, which included sweeps in the area around the NTUA, also known as Athens Polytechnic.
Government spokesman Simos Kedikoglou told Mega TV that the police were simply “implementing the law”.
Police closed roads around the building at 6.25 a.m. and reopened them about three hours later.
Greece's university asylum law restricts the police's access to university ground.