The 41-year-old says that his relationship with the Portuguese was not strong enough for him to work alongside the now-Chelsea boss during his time as Real Madrid coach
Zidane enjoyed a difficult relationship with the Portuguese during his time as Madrid's sporting director, having moved into the dugout besides Carlo Ancelotti since the Italian took over.
"With Ancelotti, it’s all happened quite naturally. I spoke with him by phone a few days before he joined and we sorted everything out. That was a good moment for me, for him and for the club," Zidane told Canal+.
"I wouldn't have been able to take on that role with a coach I didn't know. I could never have been Mourinho's assistant, for example.
"And besides, he already had an assistant. It wouldn't have been right to take on the job of being his right-hand man."
Mourinho left Madrid in the summer of 2013 after an unsuccessful campaign in which he fell out with key players such as Iker Casillas and Sergio Ramos.