The duo were called up on Tuesday after Kevin Trapp and Leon Goretzka were ruled out of Joachim Low's plans due to injury.
Bayern Munich confirmed in a brief medical update posted on social media that muscle tightness led to midfielder Goretzka's withdrawal.
Leno and Gnabry were not part of the Germany squad that flopped at the World Cup, where Low's men were surprisingly dumped out in the group stage.
Marco Reus, Antonio Rudiger and Kai Havertz had already pulled out through injury, with Emre Can having been called in as a replacement.
Schalke striker Mark Uth was the only surprise name on the original call-up list as Low has turned to a veteran side in advance of two tough tests in the Nations League.
Uth, 27, joined Schalke on a free transfer in pre-season after catching the eye with Hoffenheim last term, scoring 14 times in the Bundesliga to help Julian Nagelsmann's side qualify for the Champions League.
He is yet to score for his new club despite featuring nine times in all competitions, with Schalke alarmingly second from bottom in the Bundesliga having won just once in six matches.
Germany take on Netherlands in Amsterdam on Saturday before travelling to Paris to face World Cup winners France three days later.
Low's side drew their League A Group 1 clash with Les Bleus 0-0 in Munich last month in what was a promising response to their World Cup failure.