Manuel Neuer must "scale back his workloard for the time being" due to a muscle problem in his left calf, his Bayern Munich club said in a statement on Sunday.
Neuer was substituted during Saturday's Bundesliga closer against Cologne after picking up an injury.
It's unclear whether he will be available for the German Cup final on May 23 or for a potential trip to the United States, Canada and Mexico for the World Cup.
Neuer retired after Euro 2024 but according to media reports he will return to the national team and be Germany's number one at the tournament if he's fit.
Germany coach Julian Nagelsmann avoided making a definitive statement on the speculation during an appearance on the ZDF programme Sportstudio on Saturday evening.
The former Bayern coach said several times that he wanted to speak with all players first, adding that "that hasn't happened yet."
Hoffenheim's Oliver Baumann is currently the starting Germany goalkeeper.
Nagelsmann plans to announce his World Cup squad on Thursday.