Madrid will play Villarreal in La Liga on Saturday without their captain after he suffered a hamstring strain in Spain's 6-0 win over Germany, while fellow centre-back Raphael Varane is also a doubt with a shoulder problem picked up with France.
"What I can say because I see it, is that the calendar is too much," Zidane said in a news conference on Friday. "I think about the players' health. With all the games we have, they never stop. I'm worried."
Sources have told ESPN that Ramos is expected to be out for at least 10 days -- missing at least the Villarreal game and next week's trip to face Inter Milan in the Champions League, and potentially the following weekend's match with Alaves.
"When any player gets injured, it is bad news," Zidane said. "We know Sergio won't be here. We want him to get well soon, the others are here and we're thinking about the game. When you see your players get injured, it is the worst news for a coach."
Zidane suggested governing bodies such as FIFA, UEFA and La Liga should listen more to the concerns of players and managers.
"Coaches need to feel heard," he added. "We have meetings to try to change things. I've said how I feel, what I think.
"For the health of the players and the game, it's important that we play well, that the players can rest, and that we put on a good show. But above all, the players' health."
Recent weeks have seen increased speculation about the future of club captain Ramos, with his contract expiring next summer and little progress made yet on a new deal.
ESPN reported earlier in November that early talks have begun over an extension, but Real Madrid's financial situation has made discussions difficult.
"We always want him with us," Zidane said. "For what he is, what he brings, we know his importance.
"I hope the situation with Sergio and the club is resolved fast for the good of everyone and for me as the coach, of course."