Ntep picked up a hamstring injury on Sunday with his club Rennes during a 1-1 draw with Monaco in the French league.
Lacazette has so far failed to reproduce the form that made him the league's best striker last season but is showing signs of improvement. He scored his first goal from open play since last April over the weekend as Lyon beat Reims 1-0.
As host, France has automatically qualified for Euro 2016 and must rely on friendly matches to get ready for the tournament. The team hosts Armenia on Thursday before a trip to Denmark three days later.