The move - which will see the restrictions apply to Lloyds Bank, Bank of Scotland, Halifax and MBNA customers - has been put into action on Monday (05.02.18) following a sharp decline in value of digital currencies.
As reported by the BBC, there are fears people could run up debts, leaving Lloyds concerned it may end up having to foot the bill for unpaid amounts if the prices continue to fall.
The ban will only apply to the eight million credit card customers signed up with the banking group, and not to its debit card users.
A spokeswoman said: "We continually review our products and procedures and this is part of that."
While Bitcoin was down 30 per cent last week at $8,291.87 per unit - its worst week since spring 2013 - it's still ahead of the $1,000 it was trading at in February 2017.
The ban comes as police have warned people about the popularity of digital currencies among criminals.
British Prime Minister Theresa May recently said: "[Action against cryptocurrencies may be required] precisely because of the way they are used, particularly by criminals ... In areas like cryptocurrencies, like Bitcoin, we should be looking at these very seriously."