Crypto-ATMs look like regular cash machines and let people buy crypto-currency, such as Bitcoin, using their bank cards.
But no company offering crypto-currency services in the UK has a licence to operate a crypto-ATM.
The FCA said all such machines must be shut down or it will take action.
According to crypto-ATM directory Coin ATM Radar, there are 81 functional crypto-ATMS in the UK.
The FCA said: “We regularly warn consumers that crypto-assets are unregulated and high-risk which means people are very unlikely to have any protection if things go wrong.
“People should be prepared to lose all their money if they choose to invest in them.”
The FCA publishes a list of companies that appear to be involved in crypto-currency but have not registered their business with the regulator for anti-money-laundering checks.
It said that since the publication of its list, 110 of the crypto companies had ceased trading.