The rallies would be held in Berlin and Frankfurt, the union that represents about 1,000 cabin crew at Ryanair in Germany said in a statement.
Discussions over possible walkouts were continuing, the union said, with a decision due to be announced on Thursday evening.
Ryanair workers in several European countries including Portugal and Spain have said they will stage a 24-hour strike on Friday.
(Reporting by Nadine Schimroszik; Writing by Tom Sims; Editing by Tassilo Hummel and Edmund Blair)