The Spanish international picked up the complaint during Wednesday's Champions League win over AC Milan, and was left out of Vicente del Bosque's squad for their upcoming friendlies in Equatorial Guinea and South Africa.
"Gerard has had a groin problem for a while now and as far as we can we will try and be careful in how we use him," Argentine Martino told a news conference.
"It's in our interest that he arrives at the latter part of the season in good shape."
Another Spanish international, midfielder Sergio Busquets, was rested.
Unbeaten Barca, who visit 19th-placed Betis on Sunday, top La Liga with 34 points, one ahead of second-placed Atletico Madrid and six clear of Real Madrid.
Atletico visit promoted Villarreal on Sunday, and Real host Real Sociedad on Saturday.