Reports in Germany alleged Mane hit Sane in the face following Tuesday’s 3-0 Champions League defeat by Manchester City at Etihad Stadium, BBC Sport reported.
The pair reportedly had to be separated by team-mates after the altercation.
Bayern said Senegal forward Mane has been dropped because of “misconduct” and confirmed he will also be fined.
“Sadio Mane, 31, will not be included in the FC Bayern squad for this Saturday’s home match against 1899 Hoffenheim,” said Bayern in a statement on Thursday.
“This is due to his misconduct after Bayern’s Champions League match at Manchester City. Mane will also be given a fine.”
Bild said former Liverpool player Mane, a two-time African footballer of the year, had complained about the way Germany winger Sane spoke to him after the defeat.
After flying back to Germany, Mane was picked up privately at the airport while Sane got the team bus.
Both Mane and Sane were back in training together on Thursday morning.
Neither player has yet commented on the alleged altercation.
Bayern host City in their quarter-final second leg next Wednesday.
Mane joined Bayern from Liverpool for £35m on a three-year contract in June, shortly before prolific striker Robert Lewandowski left the German champions for Barcelona.
He scored six goals in his first seven matches in all competitions for Bayern but has not scored since October, struggling to replicate the Poland international’s exploits.
Mane, who scored 120 goals in 269 appearances for Liverpool, missed the Qatar World Cup because of a knee injury picked up while playing for Bayern in November, which also kept him out of nine club games.