There were violent clashes between protesters and gardaí outside the Department of Finance offices at Merrion Row on Wednesday.
The Garda Síochána Ombudsman Commission (GSOC) confirmed it had received 12 complaints by close of business yesterday.
It is understood the complaints are varied but some relate to allegations of excessive use of force by gardaí.
GSOC is examining the complaints to determine if they are admissible.
The commission will then decide if they will conduct a criminal investigation against certain gardaí or whether it is more an issue of misbehaviour.
The clashes occurred while leaders of the Union of Students in Ireland (USI) were giving speeches at the main protest around the corner, outside Government buildings on Merrion Square.
The USI disassociated themselves from the fringe protest. This protest was organised by a grouping called Free Education for Everyone (FEE), based in NUI Maynooth and NUI Galway and the Students in Solidarity Network from UCD and TCD.
Before the protest, these groups called for “a clearly visible left-wing presence” and said this call had been answered by the Socialist Workers Party, the Socialist Party, Workers Solidarity Movement, Éirigí and the 32 County Sovereignty Movement (aligned with the Real IRA).
Garda public order units dressed in full riot gear and ordinary uniformed gardaí clashed with the protesters outside the department building after a group of students entered and occupied the small foyer.
Flags of the Socialist Workers Party and the Workers Solidarity Movement were prominent in the foyer and entrance of the building and outside on the street.
Flags of republican party Éirigí were visible in the crowd and members of 32 County Solidarity Movement were also there.
During a standoff a succession of objects were thrown at gardaí by some people in the middle of the crowd, injuring three gardaí, one of whom suffered a broken nose.
The public order unit set up a cordon at the entrance, while other members of the unit forcibly ejected those who occupied the building.
Film footage shows members of the unit using their shields to force students back. Footage also shows some members striking protesters sitting on the ground with batons.
FEE said afterwards: “There was no act of violence carried out by those protesting at the department, and any violence outside was instigated by the inept response of the gardaí. Students sitting on the road in protest were baton charged repeatedly by gardaí, with many suffering injuries.”
The Socialist Workers Party accused the gardaí of assaulting some of their members and other protesters.
Éirigí claimed that “blood flowed on the streets of Dublin” as a result of Garda baton charges.