According to initial estimates, the company said Monday it would have to cancel some 30 percent of domestic and medium-haul flights and fewer than 10 percent of long-haul flights.
Launching a strike in the middle of summer is "total nonsense", said AirFrance CEO Frederic Gagey.
Last summer Air France flew an average of 1,000 flights a day, carrying some 140,000 passengers.
Flights to European destinations, north Africa and Israel will be affected, as well as some routes in Asia and Africa, the company said.
At issue is the duration of an accord setting working rules, pay and promotions that is due to expire in October.
Management has proposed an extension of 17 months, while the unions are demanding a duration of between three and five years.
In late June the new CEO of the Air France-KLM group, Jean-Marc Janaillac, warded off a pilots' strike that would have been the second such stoppage during the Euro football tournament.
Their unions dropped their strike call after Janaillac proposed freezing new pay rules opposed by the pilots in exchange for a four-month truce.
The pilots' last strike, which grounded around 20 percent of flights on June 11-14, hit France as it was gripped by social unrest over a series of disputed labour reforms from the Socialist government.
The SNPNC-FO and UNSA-PNC unions say they represent 45 percent of the flight attendants.
Flight crews account for 13,600 of Air France's 50,000-strong workforce.
What Air France advises if you are affected by the strike
The following information is taken from the Air France website.
What you can do if you need to postpone your trip.
If you wish to postpone your trip, we offer you the following commercial measures.
If you have planned a trip on an Air France flight between July 27 and August 2, 2016:
- You can bring your trip forward on 25 or 26 July 2016 inclusive, or postpone your trip from 3 to 12 August 2016 inclusive. You can change your reservation at no extra cost in the same class of travel.
You can make these changes on the website in the "Your reservations" section, on our mobile sites or from your travel agent.
- You can also postpone your trip beyond 12 August, 2016, change your origin or destination or if you no longer wish to travel, you can receive of a non-refundable voucher valid one year on Air France, KLM or Hop! In this case, you may contact your travel agent.
What should you do on the eve of your trip?
Before you go to airport, if the flight is "operated by Air France", we recommend that you check the information of about your bookings on our website or mobile app in the "your reservations" section.
If your reservation is cancelled, we recommend that you do not travel to the airport. Our staff will do their utmost to offer you an alternative solution.
Otherwise, you will be able to change your flight independently on our website. If you wish, you can also contact your travel agent or our teams who are mobilized to assist you in seeking an alternative solution (in the "Contact us" section).