TAOISEACH Micheál Martin has warned young people that "no-one is invincible" from Covid-19 as he urged people to behave responsibly this weekend.
Mr Martin said crowded indoor gatherings and house parties are "a problem" has he also announced that face masks will be finally be mandatory on public transport from Monday onwards.
Major concern was sparked by scenes of crowded streets outside pubs in Dublin last week.
And many of the new cases of coronavirus have been among younger people in recent days.
Mr Martin said there is worry at breaches in social distancing last week and he also noted that Gardaí have taken cases against some pubs which were not complying with Covid-19 rules.
He said: "The Gardaí will be out and about again this weekend to prevent a re-occurrence of what happened last weekend."
Mr Martin said: "People have been very extremely good and effective in complying with all of the guidance... and we appeal to people please continue that."
He added: "It's been a difficult journey for people. But as we have reopened I think the responsibility is on us all, personally, and as groups to just behave responsibly, particularly in terms of gatherings and in terms of social distancing."
"One can still enjoy oneself but this is a very dangerous virus.
"It can damage people's health for quite a long time in some instances. It's not something to be taken lightly... it is extremely important that we prevent as many people as possible from getting this virus."
Asked if he had a message for young people, he sympathised with the impact the pandemic has had on their lives from the cancellation of the Leaving Certificate exams to changes at universities.
He said: "Young people have had a very difficult summer" and this has to be taken into account.
But he warned: "That said, the same advice applies to young people as to everybody else.
"The indoor gatherings are a problem. Over-crowded house parties are a problem and no-one is invincible.
"This is a dangerous virus and I say to all people, young and old to be very, very conscious of that."
Mr Martin added: "With clever precautions young people can still enjoy themselves without having to put themselves in harm's way."
He said the public health advice on indoor gatherings will probably "strengthen".
Health Minister Stephen Donnelly said: "People have had to stay at home for a long time, and then when everyone started going out again it rained on us for three weeks.
"It's sunny. So go out and have a good time.
"People need to have a good time but please, please, please, maintain social distancing."
He also asked that people continue to download the HSE's Covid-19 tracing smartphone app.
Mr Martin said the order making face coverings mandatory on public transport will be signed this evening and it comes into effect on Monday.
He also said: "We encourage people outside of public transport system we encourage people to wear masks in crowded indoor gatherings and again where social distancing is not possible."