The 34-year-old, who was substituted in Sunday’s win over Lyon, had a scan on Tuesday and will be assessed further on Thursday.
PSG, who are top of Ligue 1 after six straight wins, face Manchester City in the Champions League on Tuesday.
Messi has featured in three games following his summer move from Barcelona.
Before hosting City, Mauricio Pochettino’s side face Montpellier on Saturday.
The PSG boss revealed the injury was the reason why he took Messi off after the Argentine appeared unhappy at being replaced.