"I like the currency of the United States," Trump told host Stuart Varney.
He argued that investing in cryptocurrencies "hurts the United States currency" and "we should be invested in our currency."
Tuesday’s attack on cryptos was the second made by the former president on FOX Business as Bitcoin and other cryptocurrencies remain unregulated within the U.S. financial system.
In June, Trump told Varney that Bitcoin seems like a "scam" and the euphoria surrounding the world's largest cryptocurrency is watering down the U.S. dollar.
"The currency of this world should be the dollar. And I don't think we should have all of the Bitcoins of the world out there. I think they should regulate them very, very high," Trump told Varney at the time adding, "It takes the edge off of the dollar and the importance of the dollar."
|BITQ||EXCHANGE TRADED CONCEPTS TRUST BITWISE CRYPTO INNOVATORS E||8.96||+0.70||+8.47%|
|COIN||COINBASE GLOBAL INC.||133.76||+9.04||+7.25%|
On Tuesday, Trump said cryptocurrencies "may be fake."
"Who knows what they are, but they certainly are something that people don’t know very much about," he continued.
Bitcoin has fallen from its record high of $64,888 set in April to around $47,400 on Tuesday. The cryptocurrency is still up 63% this year.
By contrast, the Wall Street Journal's dollar index is little changed this year.
Trump, during his tenure in the White House, supported both a weak and strong dollar. When the dollar is weak, it is more attractive and cheaper for foreign countries to buy U.S. goods. During his long battle with China, Trump frequently accused the nation of keeping its currency, the yuan, intentionally low to make exports cheaper.
Securities and Exchange Commission Chairman Gary Gensler has signaled he supports digital currencies, but speaking on FOX Business earlier this month he argued that the "field is not going to reach any of its potential if it tries to stay outside of our laws."
He specified that those laws include those pertaining to money laundering, tax compliance and the SEC’s "focus," which is investor protection.
Gensler provided the insight on "Mornings with Maria" as the industry has been waiting to see how the Democratic appointee will approach oversight of the crypto market, which he had reportedly said should be brought within traditional financial regulation.
During the interview with host Maria Bartiromo, Gensler called cryptocurrencies "innovative technologies," but also pointed out the potential risks associated with the evolving industry.
FOX Business’ Suzanne O’Halloran contributed to this report.