Barca then host Real Betis on Sept. 17 and Celta Vigo on Sept. 24, although it is not clear if Pedri will be ready to play a part in those fixtures or if he will have to wait until the games against Mallorca and Sevilla which follow.
"Pedri has a right quadriceps injury," Barca said in a statement. "He is unavailable for selection and his recovery will determine his return."
It is the latest in a string of issues Pedri has picked up since playing 52 games in his debut campaign with Barca in 2020-21 in addition to the European Championship and Olympic Games with Spain.
The former Las Palmas midfielder missed 41 games for club and country in 2021-22, mainly due to a hamstring injury which kept him out for several months.
Pedri had started both Barca's games this season, a goalless draw at Getafe and a 2-0 win over Cadiz on Sunday, scoring the opening goal in the latter.
It is the second injury setback Barca have suffered in the last week, with defender Ronald Araújo also ruled out until after the September international break with a hamstring injury.
Barça are in LaLiga action on Sunday when they travel to Villarreal.