Tánaiste Micheál Martin has condemned the latest violence in Belfast, saying that what he described as an "attack on democracy" by a small group of people was "extremely concerning".
Speaking in Killarney, Co Kerry, the Fianna Fáil leader said the recent violence in Belfast, and concern around further incidents which could take place this Friday, must be brought to an end.
The PSNI said officers came under sustained attack, and at one stage petrol was poured over a police Land Rover and set alight.
Police deployed two plastic bullets, with one rioter struck on the hand.
"It is extremely concerning that we have certain minority cohorts of people who are determined to engage in violent activity and who are targeting citizens of our country for such an attack, and I think the attack on people and property in Belfast has to be condemned," he said.
He added: "What's happening in Britain is extremely worrying. The vast, vast majority of people want no truck with this.
"There's no issue with legitimate protest, with the legitimate articulation of views and perspectives. But the kind of violence we're witnessing on our streets now and the aggression is simply unacceptable, and the role of social media as well in terms of facilitating the articulation of such violence and aggression, is equally something that has to be dealt with by governments."
Asked if gardaí should be identifying people who may be traveling from the Republic to Belfast to take part in future riots or protests, the Tánaiste said gardaí will have "a comprehensive array of approaches" to this, adding that they are "on top of this in terms of what is occurring on our streets at the moment".
Mr Martin cited Nobel Peace Prize winner John Hume in saying that people should respect difference, "because in respecting difference are the true foundations of peace and harmony in society."
"That is at the essence of what we're witnessing at the moment. We need to reclaim that territory of respect for difference, first and foremost."
The Tánaiste said that legitimate protest is fine, but that the attacks and violence seen in Belfast in recent days are "an attack on democracy and an attack on our quality of lives, and we have to deal with that."
Asked about how some of those involved in recent incidents have been carrying tricolours, the Tánaiste added: "Unfortunately ... we've had many, many groups of people abusing the tricolour and to have the tricolour abused in this manner again is appalling.
Read more: PSNI condemns 'disgraceful scenes of violence' in south Belfast
DUP minister Gordon Lyons said there is "no justification whatsoever for this violence", adding that he condemns it "in the strongest possible terms".
"I want to send my thoughts to those who have been most affected. Those affected personally and those whose businesses have been affected as well," he told the BBC's Good Morning Ulster programme.
"There is never any justification for this type of violent behaviour. There is no justification for attack on the police and it needs to stop and it needs to stop straight away, and I'm glad that we do have united political leadership right across all parties on this in Northern Ireland."
Asked about the motivation behind the original anti-immigration protest on Saturday, Mr Lyons said legitimate concerns should be heard but that there is no justification for violence.
Sinn Féin MLA for South Belfast Deirdre Hargey said there seems to be mainly young people involved in the unrest, but it is not clear if they are being directed by others.
Speaking on RTÉ's Morning Ireland, she said she got a call last night that a crowd had assembled and was headed towards the Islamic centre in the south of the city and later there were disturbances in the nearby Sandy Row area.
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She said it was "a tense situation but the police in the early hours, brought it under control".
When asked if a planned protest on Friday will be stopped, Ms Hargey said that local politicians are engaging with the police in relation to that, as well as gardaí as some people travelled from the Republic to take part in the protests.
Yesterday, it was confirmed that the Stormont Assembly is being recalled for a special meeting to discuss the violence and disorder following the protest in Belfast on Saturday.
The special meeting has been arranged following a proposal from the Alliance Party which was backed by Sinn Féin, the Ulster Unionists, SDLP and Independent Unionist Claire Sugden.
A statement confirming the recall came shortly after Stormont First Minister Michelle O'Neill and deputy First Minister Emma Little-Pengelly issued a joint statement saying there must be a "zero tolerance approach to racism and wanton destruction".
Additional reporting: Fiachra Ó Cionnaith
