Cavani scored two brilliant goals against Portugal in Uruguay's 2-1 last 16 victory on Sunday, before limping off with the assistance of Cristiano Ronaldo.
Now he is fighting for a full recovery so he can again lead the line with Luis Suarez against France in Nizhny Novgorod.
A scan showed swelling in Cavani's left calf muscle but no torn fibres, the FCF said in a statement.
"The player remains in pain. He will continue to do individual work and rehabilitation. His evolution is being monitored," it said.
"The rest of the squad is fine."
