Police used water cannons and sound grenades on protesters demanding certificates for all candidates who took part in the viva voce of the 18th teachers' registration exam.
The incident took place in front of the National Press Club on Sunday.
Earlier, at around 11am, police blocked the protesters when they tried to move from the front of the Press Club.
Although police repeatedly asked them to leave, the protesters continued chanting slogans.
At 11:23am, police dispersed them by firing water cannons and sound grenades.
The protesters claim that although they passed both the preliminary and written phases of the 18th teachers' registration exam, a record 20,688 candidates were deliberately failed in the viva.
In protest, they began a sit-in program in front of the NTRCA office on June 15.
Their demand is that the results be re-evaluated and certificates be issued to all candidates who took part in the viva.
