Bale, Isco and Marcelo have all endured difficult seasons under Julen Lopetegui and Santiago Solari, with Bale heavily criticised for his form while Isco and Marcelo have been dropped.
Zidane's return puts Bale's future in further doubt, given the pair's relationship became strained last season, before the Welshman said he was considering his future at the club.
"I am not going to talk about Bale's season, I only talk about the 11 games we have left," Zidane said on Friday.
"We all know the player that Gareth is. I am counting on him like everyone else, we are ready and Gareth is ready."
Whether Zidane's words come with a place for Bale in his first starting line-up at the Santiago Bernabeu remains to be seen, as Madrid look to rebuild following a turbulent few months.
Isco never started a single La Liga match under Solari while Marcelo increasingly found his place at left-back taken by the 22-year-old Sergio Reguilon.
"Isco wants to play and nothing else," said Zidane, who added on Marcelo: "He has also not played much but he is a professional. We have to respect everything the previous coaches did, it is not easy, but I am happy to see Marcelo again."
Madrid are 12 points adrift of leaders Barcelona and Zidane now has three months to assess his squad ahead of potential changes in the summer.
"I am not thinking about that, we have to think about finishing the season well," Zidane said. "You do not have to be thinking about who stays or goes, everyone has a contract here, then we will see what happens."
Zidane replaced Solari on Monday, returning to the club that he left only nine months ago after winning his third consecutive Champions League trophy.
"It's like the first day again," Zidane said. "Even if it's not new, it will be something different, it does not have to be the same thing. I am excited to have a new adventure."
Paris Saint-Germain's Kylian Mbappe and Neymar have been among those linked with a move to Madrid, with Real Madrid president Florentino Perez joking on Monday, "I would like them both".
"You are always delighted to coach the best players," Zidane said. "We know the quality those two players have but what interests me is tomorrow's game, nothing more."