The protesters also blocked the Risala Road.
Talking to journalists, teachers Ahmad Arisar, Kazim Raza, Rasool Bux, Iqbal Jamali, Hussain Bux Kaka and others said the Nazim of union council-9, City, Tanvir Siddiqui, on Wednesday entered the office of headmaster Bashir Memon and manhandled him.
They said the Nazim frequently visited the school and misbehaved with teachers and threatened to have them sacked.
The teachers said they would continue their protest till the Nazim offered an apology to the headmaster.
The Nazim could not be contacted for his version.