Defensive midfielder Tchouameni has a foot issue while defender Mendy suffered a shin injury. Both started Real Madrid's 2-0 win over Real Betis on Sunday, with Mendy substituted in the second half.
Lazio midfielder Matteo Guendouzi and Aston Villa left-back Lucas Digne have been called up as their replacements. France play Italy on Friday at the Parc des Princes and face Belgium three days later in Lyon.