The Uruguay international striker appears to be a major injury concern for Tuesday's trip to Old Trafford after suffering the injury on Saturday.
Cavani appeared to hurt himself while scoring a penalty in PSG's 1-0 Ligue 1 win over Bordeaux and he was substituted straight afterwards.
Tests have revealed he has damaged a tendon in his hip but the French champions have not put a timescale on how long Cavani could be out.
An update on PSG's official website said: "Medical examinations have revealed an injured tendon in Edinson Cavani's right hip.
"The treatment of this injury and the length of his unavailability will depend on the evolution of the injury over the coming days."
The news is another blow for PSG boss Thomas Tuchel, who is already without Neymar for both legs of the last-16 Champions League tie due to a metatarsal injury.