Jet2.com and Jet2holidays have suspended flights and holidays to all amber list destinations up to and including July 18.
The sister brands said the decision was taken because they expect the next UK government review of the traffic light status of overseas destinations to be on or around July 15.
A statement said: “We welcome recent news reports about vaccinated people being able to travel to amber list destinations without having to quarantine and we look forward to further updates on this as soon as possible.
“The vaccination programme has been a huge success, so it is time for us all to enjoy the benefits of that.
“Where customers are affected by any programme changes outlined above, we will automatically cancel their booking with a full refund, and our team of travel experts will be in touch to help them to rebook their summer getaway.”
More: Jet2 restarts holiday programme to green list destinations
Don’t fall into ‘the trap of new normal’, warns Jet2 boss
Jet2 boss ‘disappointed’ by Turkey red list decision
Jet2 boss foresees ‘very tough’ times ahead for agents
The statement said the move does not affect green list destinations and the brands resumed operating to those countries from Thursday (July 1).
However, Turkey remains on the red list, so the brands have suspended all flights and holidays to the country up to and including July 21.
The statement added: “We will of course continue to review our entire programme in line with updates from the government.
“With the government looking to unlock restrictions on July 19, we expect the same approach to international travel.
“If we are to use the term Freedom Day, then people must have the freedom to travel to safe destinations overseas.”