Bale was jeered by sections of the Real Madrid support during Sunday night's La Liga clash with Valencia, with the Welshman struggling to make an impact before being substituted with the score still at 1-1.
Zidane, however, has said that his team still "rely" on the 28-year-old.
"He's a key player in the squad," Zidane told reporters. "Gareth is Gareth. We keep working hard and we rely on Gareth, just as is the case with the other players.
"Gareth's situation is good. He had scoring opportunities but did not convert them. We're going to keep working on this. I can't criticise my players, quite the contrary. I'm very happy with their work."
Bale has scored 68 goals in 154 appearances for Real Madrid since moving to the Bernabeu from Tottenham Hotspur in the summer of 2013.