The airline is dealing with a staffing crisis due to a Covid spike, it said.
Aer Lingus has said at least 21 of its flights into and out of Dublin Airport have now been cancelled today.
They include nine return services, with staff absences again mostly to blame with one caused by industrial action in France.
British Airways, and one Air Portugal flight has also been cancelled.
It comes as airports and airlines across the continent deal with staff shortages.
In a statement Aerlingus said: “Aer Lingus wishes to apologise to those impacted and teams at the airline are working to reaccommodate impacted passengers on the next available services as efficiently as possible.
“Aer Lingus anticipated the return of demand for travel once Covid restrictions were removed and built appropriate buffers into our plans in order to deal with a reasonable level of additional disruption.
“System pressures and ongoing issues at some airports and among third-party suppliers have created considerable operational challenges which have been compounded by a significant spike in Covid cases in recent days.”
Meanwhile, rival Ryanair said strike action by Spanish staff at Barcelona and Malaga had not affected any Irish flights.
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