Sergio Busquets put Barcelona ahead on the stroke of half-time before an own goal from Real Sociedad's Enaut Zubikarai in the 60th minute effectively ended the contest.
Martino told a press conference: "We didn't dominate to the point that would allow us to think we could have killed off the tie."
The Catalan side came into the match following a shock 3-2 home defeat to Valencia but Martino opted to name a largely unchanged line-up, which saw Jose Pinto replace Victor Valdes.
Martino added: "The players that played against Valencia needed to play in this match because if I had taken any of them out perhaps I would lose a player for the future."
Overall the former Newell's Old Boys coach was pleased with his side, especially after the defeat at the weekend.
"(We played) a good game, we didn't take any risks," he added. "We were a bit apprehensive because of Saturday's game against Valencia."
He was also happy with his "team's organisation against Real Sociedad, their eagerness to score the second goal and their patience".
He added: "We scored twice, probably thanks to chance and not because of how we played. He's always performed well since he arrived at Barcelona."
Martino also insisted he is not concerned that star striker Lionel Messi was not find able to find the net.
He added: "I'm not worried about Messi scoring goals. He had three clear chances today, and one of them the keeper saved from point blank range - he'll score again soon."