"I'm not looking at the same information they're looking at, but given what I do know ... I'm confused about how they think they can possibly protect their guests and their employees," the Disney heiress said on "Squawk Box."
Disney, granddaughter of company co-founder Roy Disney, said that reopening the parks near Orlando puts employees in an especially difficult position.
"I certainly know people who work there who are very uncomfortable, who have conditions like asthma and diabetes that put you at high risk, who are literally deciding whether they want to go back to work or buy food," said Disney, an Emmy Award-winning filmmaker who is CEO of production company Fork Films.
Disney was among the first parks to close in Florida in mid-March as the nation's Covid-19 outbreak accelerated. It was one of the last to reopen.
Last week, Josh D'Amaro, chairman of Disney parks, told CNBC that the company feels "really good" about the safety precautions it put in place. "There's a lot of trust here, both from our cast members and our guests, and we've got a responsibility to deliver on that trust," D'Amaro said.
Asked whether she conveyed some of her concerns to the entertainment company's leadership, the philanthropist and activist said, "The lines of communication are not robust."
— CNBC's Sarah Whitten contributed to this report.