"I'm not a big fan of what they're doing there," Cuban said of Facebook's Libra coin. "I think it's a big mistake."
Cuban, owner of the Dallas Mavericks and a "Shark Tank" investor, said he's not so much concerned with the impact on U.S. markets but at a global level.
"I think globally and in countries where there isn't a lot of rule of law, or a lot of government stability, or currency stability, then it could be dangerous," Cuban told CNBC's Deirdre Bosa in an interview that began airing on Friday.
"There's going to be some despot in some African country that gets really upset that they can't control their currency anymore and that's where the real problems start occurring," he explained.
Cuban has joined a series of government leaders and high-profile bankers in criticizing the social media giant.
In a series of tweets, President Donald Trump on Thursday said that he's "not a fan" of cryptocurrencies and said Libra "will have little standing or dependability."
He also said, "If Facebook and other companies want to become a bank, they must seek a new Banking Charter and become subject to all Banking Regulations."
Appearing on Capitol Hill over two days this week delivering testimony and taking questions on the economy, Federal Reserve Chairman Jerome Powell said he has "serious concerns" about Libra.
French Finance Minister Bruno Le Maire and Bank of England Governor Mark Carney have also questioned Libra.
Last month, Facebook announced its ambitious endeavor to create a digital coin, with launch plans in the first half of next year. Libra will not be run by Facebook but by a nonprofit association supported by a range of companies and organizations, including Visa, PayPal, eBay, Lyft, Uber, and Spotify.
David Marcus, the Facebook executive behind the effort, told CNBC on the day of the announcement, June 18, that consumers should not be worried about the social media network gaining access to their financial data.
Facebook did not immediately return a request for comment.