The 32-year-old has helped propel the already illustrious Spanish outfit to new heights since joining from Manchester United in 2009.
On Saturday, Los Blancos became the first club to retain the Club World Cup after Ronaldo scored a free kick in the 1-0 final win over Gremio.
Although the Portuguese is tied to Real until 2021, Zidane insists that the club should pull out all the stops to keep him at the Bernabeu.
"Obviously, but at the right moment," the Real manager told Sky Sports News when asked if Ronaldo should be rewarded with another new contract.
"For us it is fundamental Cristiano stays. He is at his club, his home and no one can do what he keeps doing, so hopefully he stays here until he retires."
Ronaldo penned his last contract with Real in November last year.