The 27-year-old's current deal with the Blancos expires in two years' time, but his long-term future at the Santiago Bernabeu has been thrown under the spotlight following his claim earlier in the season that he was unhappy with life in the capital.
Nevertheless, the Argentine is desperate to see Ronaldo prolong his stay at Madrid beyond 2015, citing that the winger is a player they need to keep if they are to enjoy further success in the future.
"He has to decide," he told reporters. "He still has a contract with the club and truly is a great player - one that Real Madrid needs - so I think it'll make everyone happy if he signed a new contract. But it is his decision."
Di Maria has found playing time harder to come by this season, but insists he is fully fit and ready to fight for his place in the first team again - starting with the first leg of the side's Copa del Rey quarterfinal tie against Valencia.
"I'm feeling so good and working to be at 100 percent," he added.
"I haven't played in the last few games but that's the coach's decision. I can only work day by day and make sure I'm ready to play.
"I think it'll be a really difficult tie. If we don't get a good result at home, we could go out, and Valencia are a really tough team.