Speaking after Real Madrid's 3-1 friendly loss to Bayern Munich in Houston when Bale was omitted from the 28-man squad, Zidane told reporters Saturday: "We hope he leaves soon. It would be best for everyone. We are working on his transfer to a new team.
"I have nothing personal against him, but there comes a time where things are done because they must be done."
The reply from Bale's agent, Jonathan Barnett, was swift.
"Zidane is a disgrace. He shows no respect for a player that has done so much for Real Madrid," Barnett told AFP.
He echoed Zidane in saying a transfer was being worked on.
Bale, who joined Real Madrid from Tottenham in 2013, is reportedly weighing a return to the Premier League or the Chinese Super League.
"It's nothing personal," added Zidane. "I've not got anything against him. We have to make decisions and change things. That's all there is to it."
Bale's impending move and Neymar's potential departure from Paris Saint-Germain are the two biggest transfer sagas of the European off-season. Neymar is being widely tipped to return to Lionel Messi's Barcelona.
Bale endured a difficult campaign last season, partly because of injuries. He was booed by the home fans and started only five league games after Zidane -- the former World Cup winner and footballer of the year -- was reappointed manager of Real Madrid in March.
Bale netted eight goals in La Liga, half his total from the previous season and well below the 19 goals he tallied in the top division in 2015-2016.
Bale helped Madrid win four Champions League titles -- no side has won more than Los Blancos' 13 crowns -- and scored one of the most famous goals in the history of the competition's finals in 2018 against Liverpool.
His spectacular overhead kick in the 64th minute turned out to be the winner in the 3-1 victory over the Reds.
Like Bale, Real Madrid had a difficult time last season, finishing third and a distant 19 points behind archrival Barcelona. And in the Champions League, the defending champions were knocked out by Ajax in the last 16.
In an attempt to overturn its fortunes, Real Madrid signed Belgian star Eden Hazard from Chelsea in June.
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