Lufthansa is apologising to customers ahead of time for the widespread disruption expected Friday during a 24-hour walkout by flight attendants.
Still the German airline is making it clear it is up to the union to return to negotiations.
Lufthansa has cancelled about 1,200 flights Friday, two-thirds of its schedule.
Ads in several German newspapers on today said: "We regret this very much and apologise for it."
The airline added: "We consider this strike disproportionate."
On Tuesday, several-hour walkouts by Lufthansa cabin crews in Frankfurt, Munich and Berlin caused about 350 flight cancelations.
Lufthansa and the UFO union are at odds over pay and conditions as the airline struggles with increasingly tough competition from European budget carriers and government-owned Gulf airlines.
Lufthansa underlined hopes of "more competitive structures in future".
