A five-day Air France strike that began Thursday was expected to cause the cancellation of 30 percent of the carrier's flights, the company said.
The strike, scheduled to end Monday night, has been called by flight attendants over issues of pay and working conditions.
Air France initially said that only 10 percent of French and European flights would be affected by the strike, and that long-haul flights would not be disrupted.
But once the protest was under way, Air France said more flights were affected than had been expected. A spokeswoman said some long-haul flights had also been canceled.
Air France said it would allow clients to postpone flights during the strike with no penalty.
Travelers can use their ticket as a voucher for another Air France flight to the same or another destination, for a flight on another airline, or for train travel in Europe.
The company said it would reimburse the tickets of clients unable to find a suitable travel alternative.