The 22-year-old Spanish international is expected to be sidelined for at least four weeks, missing three upcoming matches for Barcelona, club sources indicated.
Pedri would also miss Spain's crucial World Cup qualifiers against Georgia and Turkey in November.
"First team player Pedri has suffered a tear in the distal biceps femoris muscle in his left thigh. The player's recovery will dictate his return to action," Barcelona said in a statement.
The injury compounds Barcelona's struggles, with 12 players sidelined since the start of the season. Key absentees include Robert Lewandowski, Gavi, Raphinha, Marc-Andre ter Stegen, and Dani Olmo.
Barca are second in LaLiga with 22 points, trailing leaders Real Madrid by five points.