Gardaí say a poster, offering a €1,000 reward for reporting house parties, is fake.
It appeared on social media after being attached to a lamppost along the canal Phibsborough in recent weeks.
The poster asks people to ring an 1800 freephone number but Gardaí say it hasn't been issued by them.
Officers have had to break up a number of gatherings since Covid-19 restrictions came into force in March.
This at Cross Guns is new. The 1800 no *is* the Garda Confidential Line but is this an official communication? pic.twitter.com/d14ypmLF7E
— Stephen Bourke (@AnBurcach) August 6, 2020
It comes as public health doctors warn people against hosting or attending house parties to stop the spread of Covid-19.
There is currently a ten person limit on visitors to private homes from no more than four different households.