A Fianna Fáil councillor in Co Clare said a complete disregard was shown for the town of Kilkee and public health guidelines on Saturday night when a party took place on the beach.
Cillian Murphy said Kilkee is trending on social media - and not for a good reason.
He told RTÉ's Morning Ireland that gardaí estimated that the age profile of those attending was between 15 and 20.
He added that there is an issue of parental responsibility in the cases of some of those who attended.
Mr Murphy said the town felt very disappointed and that a complete disregard was shown for the town of Kilkee and the health guidelines on Saturday night.
Clare County Council yesterday called for "responsible behaviour" after videos were posted to social media showing crowds of young people in Kilkee.
The council issued the appeal in a statement after, it said, "footage emerged on social media that appears to show people gathering in Kilkee in contravention of Covid-19 public health guidelines".
It said the pandemic had not gone away and it was "vital we all continue to adhere to physical distancing and other public health guidelines".
Councillor Murphy posted pictures and a message on twitter, condemning what he called "truly shocking" behaviour following the gathering.
If you are in Kilkee, the parents of a teenager and didn't know where they were last night, then this post is for you. pic.twitter.com/j80IHXilFJ— Cllr. Cillian Murphy (@Tri2bResponsibl) August 2, 2020
Chief executive of Clare County Council, Pat Dowling, said: "Young people must remember that anyone can contract the virus.
"There must be no repeat occurrence of the scenes shown on social media, in Kilkee or anywhere else in Co Clare."
Gardaí in Kilrush confirmed to RTÉ that nine people had been arrested for public order offences in Kilkee, Co Clare over the course of yesterday evening.
Two male youths were released and will be dealt with by way of the Youth Diversion Programme. Two men and one woman have been dealt with by way of adult caution.
One man was released without charge.
Three men have since been charged and are due to appear before Kilrush District Court (sitting in Ennis) on 15 September next.