A number of planes due to take holidaymakers from the UK to Palma on the Spanish island of Mallorca are departing from Berlin instead, the airline said.
The removal of Portugal from the UK Government’s green list means people returning from every major viable tourist destination must self-isolate.
The majority of countries, including Spain, are on the amber list.
Travellers returning from amber locations must take a pre-departure coronavirus test, plus two post-arrival PCR tests costing around £100, and self-isolate for 10 days.
A number of industry experts believe the delay in the next easing of domestic rules means international travel will not be opened up before the end of July.
EasyJet said in a statement: “With 50% of easyJet’s flying intra-Europe, we are seeing European governments are progressively opening up using frameworks in place which enable travel and much of it restriction-free.
“And this relaxation and removal of restrictions has sparked a positive booking momentum across Europe, with the majority of our bookings showing a strong swing towards Europe when in normal times it would be a 50/50 split with the UK.
“We are fortunate that we are able to redirect flying on our European network; for example, we have moved capacity from the UK to Palma to Berlin-Palma flying, and over the past week we have added 150,000 further seats to our intra-European network.
“Europe is demonstrating that a safe reopening of travel is possible and so we continue to urge the UK Government to do so urgently so our customers can reunite with loved ones or travel for a much-needed break.”