Bale was at the double as Madrid defeated Las Palmas 3-0 in La Liga ahead of Tuesday's first leg against Juventus in the Champions League.
Cristiano Ronaldo was rested by Zidane as the Madrid head coach had one eye on the quarter-final clash in Turin and Bale led the way at the Estadio de Gran Canaria on Saturday.
Bale opened the scoring in the 26th minute and added his 10th club goal of 2018 in all competitions in the second half after Karim Benzema doubled the lead with a penalty of his own.
However, Zidane refused to guarantee Welsh forward Bale a starting berth against Juventus.
"I'm pleased with his performance," Zidane told reporters. "You'll have to wait and see if he plays on Tuesday."
The victory was Madrid's fourth on the bounce in La Liga and Zidane added: "There's no such thing as a straightforward game, but it got easier for us after the first goal. Las Palmas need to pick up points, and once we'd got the first, it was a bit less complicated.
"The second half was very end-to-end, we created a lot of chances that we didn't score. It was a good game for us, we've picked up three points and a lot of the guys who don't get so many minutes played very well.
"I'm pleased with the players because after the international break we only had two days to get ready for this game."
Madrid defender Nacho Fernandez limped out of the match and was left in tears on the bench after appearing to hurt his right ankle.
"I took Nacho off as a precaution," Zidane said. "He's not feeling good, he's got some discomfort. I hope it's nothing serious, but we'll send him for a scan tomorrow and see."