In response to questions from journalists the head of state pointed out that the Algarve in particular was "unfairly punished for this decision".
"But we must continue, look ahead. What is needed in these critical situations - and I will have meetings this week with the hotel management - is resilience, resistance", added Marcelo Rebelo de Sousa.
The British government decided on 10 September to remove Portugal from the list of countries considered safe in the current context of the Covid-19 pandemic, with the exception of the autonomous regions of Madeira and the Azores, and from 12 September it will again force those returning from the Portuguese mainland to quarantine for a fortnight.
Portugal had been included in the list of countries in the so-called British air corridor three weeks ago.