Up to 100 people were found at one house party last weekend, gardaí say.
The force says they're finding groups as big as 30-40 people at house parties, despite continuing COVID-19 regulations.
To date, more than 3,300 fines have been issued to people attending or organising house parties.
Nearly 14,000 fines have been issued for non-essential travel, while more than 1,000 €500 fines have been issued for non-essential journeys to ports or airports.
This weekend marks the final weekend of the 5km travel restriction before it is extended to 20km from Monday.
Gardaí are reminding people to continue following the rules this weekend - saying both drivers and passengers can be fined for breaches of the travel rules.
Deputy Commissioner, Policing and Security, Anne Marie McMahon, said: "The vast majority of people continue to follow public health advice and regulations.
"Unfortunately, despite the constant public health advice, we are still seeing people attending house parties and other large social gatherings. Going to such gatherings puts yourself, your loved ones, and everyone else you come into contact with after of getting COVID-19.
"The best way of keeping safe this weekend is to stay home. If you are going out, please stay within your 5km, limit your contacts with others, maintain social distancing, and regularly wash your hands.”