The city council is investigating 40 complaints of properties being used illegally for holiday lets on sites like Airbnb.
Most of those are apartments.
In a statement to 98FM News, Dublin City Council says a number of enforcement letters have been sent out by the planning department.
"A number of properties we had received complaints about and issued warning letters to have ceased the use for short term holiday lets."
Last week the housing Committee released a report after looking into whether sites like AirBnb are drying up the rental stock for ordinary Dubliners.
It recommended the company registers all users with local authorities and Revenue.