The Real Madrid midfielder is in the middle of a two season loan.
"I'm not worried," Imanol told Cope after receiving an award from the Johan Cruyff foundation.
"There's no doubt Martin makes the difference, he's a top player.
"We know that he's super happy at La Real and in San Sebastian and, watching the work of the team a bit, we're all looking forward to ending this season well and playing more important competitions next season and that could be key.
"But the kid still wants to be here. He's very happy here.
"He knows that he's had a year of growth and that, after another season, he'd be much more prepared to make the next step."