Michalak suffered a neck injury in the 35-17 RBS 6 Nations win over Ireland and has been replaced by uncapped Biarritz man Peyrelongue for the visit of Italy to the Stade de France.
Maso explained that resting the Toulouse number 10 will allow him to return for the match against resurgent Wales in Cardiff on March 7.
"We did not want to take any risks," he said.
"We could have made him play thanks to injections. But it would not have been fair neither for Michalak nor for his club.
"The match against Italy is not a final, that is why we can afford to rest him now."
Jean-Baptiste Elissalde is set to take over the kicking duties for the clash with the Italians.
The scrum-half, who scored the fourth try against the Irish, will once again wear the number nine shirt, which used to belong to recently-retired captain Fabien Galthie.
"This is a good thing for Elissalde," Maso added. "He is a new player with us and he needs to play.
"The reason why we hardly changed the team is because we were satisfied with those who won against Ireland, but also because we wish to insist on continuity.
"Michalak should be back for the Wales clash."