"Cockpit regrets that negotiations have failed once again," the union said in a statement, accusing management of not wanting to reach an agreement.
"Further labour action can be expected with immediate effect. The public will be warned in advance," the statement said.
A spokesman for Lufthansa insisted that the airline had "signalled its willingness to compromise" and offered to talk about the contentious points.
No new date had been set for further negotiations, however.
"We appeal to the union not to go ahead with more labour action and to return to the negotiating table," the spokesman said.
Following three separate days of walkouts in recent weeks, Lufthansa pilots agreed to postpone a fourth warning strike last week after receiving a new proposal from management.
Lufthansa pilots can currently take paid early retirement from the age of 55. They are fighting a plan by the airline to raise the minimum age to 60 and for more union influence in decisions as to how pensions are financed.