Isco established himself as a vital part of Zidane's team last season, as Madrid went on to claim a La Liga and Champions League double.
The former Malaga playmaker saw off the competition of James Rodriguez in the process, with the Colombian loaned to Bayern Munich for two years at the start of this season.
But the current campaign has been somewhat disappointing for Isco, who has started just four La Liga games since the turn of the year.
One of those came in the 1-0 defeat at Espanyol on Tuesday, as he produced an underwhelming display and was substituted for Karim Benzema after 69 minutes, reacting in disgruntled fashion to his withdrawal.
But Zidane insists there is no issue with the player and thinks such a reaction is to be expected.
"I don't think it was anything abnormal," Zidane told reporters at a news conference ahead of Saturday's match at home to Getafe.
"He wasn't happy about coming off, but that's the case with most players. He has a great attitude, trains well and everyone at the club loves him.
"There's nothing to worry about there. If a player is angry about being substituted then that is normal."