Spanish air traffic controllers are threatening to strike at the start of the summer season.
They are planning two weekends of strikes – this weekend (July 11-12) and the weekend of July 25-26.
EasyJet said: "Like all airlines flying to and from Spain, if this action goes ahead we expect an impact to our flights during this period.
"We would like to assure our passengers that we are preparing for any disruption if the strike does proceed and will do everything possible to limit the inconvenience of this on your journey."
Air traffic controllers have already held four days of partial stoppages in June.
Enaire, which runs Spanish air traffic control, said it expects to run 80% of services during the strike periods while talks continue with the union.
According to Spanish News Today, the long-running dispute dates back to the dismissal of a controller in Santiago de Compostela for his role in wildcat strikes in 2010.
The strikes resulted in massive disruption and the military was called in to keep Spanish air traffic moving.
