The no frills airline, who's Chief Michael O'Leary recently branded Transport Minister, Eamon Ryan as a "Dunce", says the cap is damaging growth in tourism, and increasing the cost of air travel.
The cap of 32 million passengers coming into the capital, was introduced in 2007, as it was feared there would be maximum road capacity if it hit that number.
Ryanair claims no such problems exist, as the DAA has applied for approval from Fingal County Council to increase it to 40 million. However local residents groups around the airport, as well as climate activists have been against those plans.
Today's warning from Ryanair, is that if the passenger number is not increased, people will be left with higher fare costs by Christmas.
It's also warning other airlines will cut the number of seats at Dublin Airport by one million next summer.
This could have a detrimental affect on tourism and general business in Ireland.
Michael O'Leary is urging the outgoing Transport Minster Eamon Ryan to finally get directly involved.
