The Garda Commissioner says its difficult to establish who is the organiser of yesterday's protests in Dublin City centre.
He said recent demonstrations have involved a mix of groups with 'extremist views'.
11 people who attended yesterday's demonstrations were arrested for public order offences.
A large crowd gathered at a number of locations in the city throughout the day, before arriving on Grafton Street and clashing with gardaí.
An investigation into who organised the gathering is underway as it breached COVID-19 restrictions.
Commissioner Drew Harris today insisted the Garda response was proportionate.
He said: "These groups have shown a propensity to violence - we've seen in recent times there has been violence associated with these protests.
"All of these matters actually move it from policing of the COVID-19 restrictions properly into public order legislation.
"We were using public order legislation to prevent what would have been a very frightening stampede up Grafton Street."
The Garda Commissioner said the groups in question have a mix of 'extremist views', and it's hard to tell different groups apart because they have very similar views.
He observed: "What we find concerning about these groups is you see an initial call on open-source media, and then quickly they go to covert means of communicating with each other."
Commissioner Harris said the demonstrators' goal seems to be disrupt the activities of Government, and "that can't be tolerated" - adding that the force has "nobody to negotiate with" when it comes to organisers.
