Isco struck in either half to inspire Madrid to their first home league win of the campaign, but they are still seven points behind leaders and rivals Barcelona.
Zidane praised the 25-year-old for his approach, and the Frenchman expects the Spain international to get better.
"He's looking very confident. He knows how important he is to Real Madrid," he said.
"He plays as if it's a kick-about and I like that. He keeps going and if things don't come off for him, he's patient and he doesn't panic.
"He's comfortable out on the pitch, with his team-mates, and I'm thrilled that we're seeing the best of Isco more and more."
Madrid are fifth in the table after their slow start to the season, with Barca holding a five-point advantage at the top.
Zidane said the La Liga title fight would come down to much more than just another Madrid-Barcelona battle.
"It's true that this league campaign is going to be very difficult. I don't think it's going to be a fight between two or three teams," he said.
"It's good for the competition because we realise that it is the most difficult in the world and there will be more competition this year.
"The teams have strengthened well and play very well, the games are going to be more complicated and more entertaining."