Ryanair's statement comes after Britain abruptly imposed a two-week quarantine on all travellers arriving from Spain after a surge of coronavirus cases.
Ryanair says it's not planning to reduce flights to Spain after what it called the British government's "regrettable" decision to advise against all non-essential travel to the country's mainland due to Covid-19.
It comes as the airline dives into its first-quarter loss.
Britain had abruptly imposed a two-week quarantine on all travellers on Saturday arriving from Spain after a surge of coronavirus cases, a dramatic and sudden reversal to the opening of the European continent to tourism after months of lockdown.
"I think it is regrettable, very disappointing," Chief Financial Officer Neil Sorahan said on Monday following the publication of quarterly financial results.
Demanding a more flexible approach
"I have no doubt that we will see other localised outbreaks and we need to be flexible enough to deal with them as they arise over the next number of weeks and months," he added.
Asked if Ryanair would reduce capacity between the two countries, Sorahan said: "We have no plans to cut capacity in the medium term."
The Spanish government had made clear that the country remained open for tourists, with infection levels low in much of the country, Sorahan said.
Travel stocks dive
European shares slipped on Monday with travel stocks leading the declines after Britain imposed the Spanish quarantine.
Europe's biggest holiday company TUI said on Sunday it had decided to cancel all holidays to mainland Spain up to and including Sunday, August 9.
The pan-European STOXX 600 was down 0.2 percent but came off early lows.
Travel & leisure dropped 2.9 percent, and the broader index sank to a two-month low, further cementing its status as the worst performer in Europe this year.
UK shares dipped on Monday with the blue-chip FTSE 100 down 0.2 percent.
UK-based airlines and tour operators such as TUI AG, Easyjet Plc, British Airways owner IAG SA falling between 9.4 percent and 13.4 percent.