A garda has been taken to hospital after being injured during disturbances in Dublin city centre as protesters demonstrated against Covid-19 restrictions.
Three gardaí were injured in the clashes and 23 people have been arrested.
Garda Commissioner Drew Harris said that while gardaí had a planned operation in place for a protest, some people arrived "obviously intent on violence".
"They engaged in attacks on members of An Garda Síochána including, as we can see on social media, the throwing of a firework-type device," he said.
He said a firework was directed at a garda but he was not seriously injured.
"We are fortunate we did not suffer a serious injury. It was only the member's quick thinking that saved him," he said.
"You don't carry fireworks to a protest for any other purpose than to engage in violent conduct," he added.
Commissioner Harris said operations are continuing and there will be a full investigation to bring perpetrators to justice.
He said taking part in a protest is not a reason for essential travel. "We will be pursuing individuals, particularly those who formed a very difficult core to deal with," he said.
Garda Commissioner Drew Harris tells RTÉ News: "You don't carry fireworks to a protest for any other purpose than to engage in violent conduct." pic.twitter.com/f2W3j1ZnO4— RTÉ News (@rtenews) February 27, 2021
Mr Harris said there was a conglomeration of groups involved in demonstrations including anti-maskers, anti-vaccination groups, anti-lockdown groups, and elements of the far-left and far-right.
"No one group that we saw today was one set of individuals. This was groups working in concert with each other, as a group, as a mob," he said.
Protesters clashed with gardaí as they marched through the city centre and attempted to make their way to St Stephen's Green.
Gardaí used batons to push protesters away from the park and down Grafton Street.
Police clash with protestors in #Dublin City Centre after rocket fired directly at Gardaí. #Ireland https://t.co/w2EDjBZhoI— Jon Williams (@WilliamsJon) February 27, 2021
Asked if gardaí used excessive force, Commissioner Harris said: "I did not see that at all and entirely reject that. At the same time, people are free to make complaints to the Garda ombudsman.
"But what I saw was a very highly professional response in the face of a concerted effort to assault gardaí and the abuse they received was disgraceful."
He said gardaí had acted in a "proportionate manner" during the protests.
A senior officer has already been appointed to oversee an investigation into what happened.
"I am surprised at the level of violence and also the commentary made towards gardaí today," Mr Harris said.
He said An Garda Síochána will make sure that the city centre "is secure and safe for the rest of the night".
Taoiseach Micheál Martin condemned the protests and praised gardaí for their response in restoring order.
"I utterly condemn the protests in Dublin city centre today, which posed an unacceptable risk to both the public and gardaí," he said in a statement.
"What went on today was unacceptable," Taoiseach @MichealMartinTD says of a march in Dublin. He says it "flies in the face of the Covid-19 restrictions that the vast majority of the Irish people are adhering to". He also condemned the attacks on gardaí | https://t.co/88yZFeCSoY pic.twitter.com/6oqoTRWCeA— RTÉ News (@rtenews) February 27, 2021
"The large gathering, in the face of ongoing Covid-19 restrictions, showed a complete lack of respect to the people who have made huge sacrifices during this pandemic.
"Nor can we tolerate the thuggish behaviour or attacks on gardaí, who have the public's utmost respect as they continue to protect and serve our society in difficult circumstances.
"There can be no justification for the march or the violence that unfolded, and I pay tribute to members of An Garda Síochána who moved quickly to make arrests and restore order."
Tánaiste Leo Varadkar said there is no excuse for violence towards gardaí or anyone else.
Horrified to see this on our streets. Irish people have spent last year fighting Covid. There is no excuse for violence to Gardaí or anyone. This behaviour on Grafton St by a selfish few undermines sacrifices that millions have made in the last 12 months https://t.co/QI8x2dmFg3— Leo Varadkar (@LeoVaradkar) February 27, 2021
Minister for Justice Helen McEntee said there will be a special court sitting after the "unlawful protest".
"Anybody who brings a firework to a protest and intentionally aims it at a member of An Garda Síochána, they have no intention of it being peaceful," she told RTÉ News.
"Anybody who brings a firework to a protest and intentionally aims it at a member of An Garda Síochana - they have no intention of it being peaceful". Minister for Justice @HMcEntee says a protest in Dublin was an insult to those following #Covid19 rules | https://t.co/88yZFeCSoY pic.twitter.com/4yNqRaRzn9— RTÉ News (@rtenews) February 27, 2021
Minister McEntee described the protests as an insult to everyone who has "put their life and livelihoods on hold" by adhering to restrictions.
"It was an insult to our frontline workers and the thousands of gardaí who have gone in day in and day out to work with us and keep us safe," she added.
Minister McEntee said gardaí acted swiftly to similar protests and they will "continue to do their job".
In a statement, she condemned the "mindless thuggery" and said it showed a "wilful and blatant disregard for the public health rules which are needed to help us all and keep us safe".
Sinn Féin leader Mary Lou McDonald said on Twitter: "The protest in Dublin is reckless and is a slap in the face to the people of this city and beyond who have made huge sacrifices over the last year. Shocking and disgraceful scenes."
Sinn Féin's Health spokesperson David Cullinane said: "There is no place for what we saw in Dublin today.
"The virus is still in our community with multiple strains and they are highly dangerous.
"So many people are making so many sacrifices to drive down community transmission and defeat this virus. Everyone needs to continue to abide by the public health advice."
General Secretary for the Association of Garda Sergeants & Inspectors Antoinette Cunningham said she had spoken with a number of colleagues after "today's shocking scenes in Dublin".
I have been spoken with a number of @AGSI_Ireland colleagues after today's shocking scenes in Dublin...the blatant disregard for their safety & the complete disregard for public health is truly unacceptable...our Gardai and the general public deserve better after a difficult year https://t.co/D8uMTzWffX— antoinette (@antoabs) February 27, 2021
She said the "blatant disregard for their safety and the complete disregard for public health is truly unacceptable ...our gardaí and the general public deserve better after a difficult year".
Health Service Executive CEO Paul Reid offered his support to gardaí in a post on Twitter and said they had a "special bond" with the HSE.
They have been a "relentless support for us at all times, helping to keep people safe, secure, protected and healthy. We are with you all at this time and always," he wrote.