The attacking midfielder has stood by the Camp Nou coach amid speculation that he will be replaced in the summer and says the team has "failed" at key times in 2013-14
Celta coach Luis Enrique is reported to lead a list of potential replacements for the Argentine, who only took over from the late Tito Vilanova last summer.
A campaign which saw the Catalans exit the Champions League at the quarterfinal stage, lose to Real Madrid in the Copa del Rey final and fail to dominate in La Liga has seen Martino under heavy scrutiny, but Iniesta leapt to the defense of his trainer.
"For me, the coach that we have now is the best," Iniesta said to Diario Ole. "Also, I would be delighted if he stayed here for longer and showed everyone what he can do.
"The first year is a difficult one for everyone. I have always seen him with the desire and determination needed. He always believes in our chances.
"We have failed as a team at important moments. Sometimes things don’t go how you want them to.
"This isn’t because you don’t want it, it’s just how it goes sometimes. You always need to be making changes, regardless of whether you are winning trophies or not."
Barca visits Elche on Sunday. A win would mean that the Catalans host fellow title contender Atletico Madrid on the final day of the season knowing that victory would see them defend the title on head-to-head record.