"When it happens or how or anything else, I don't know", he said in an interview with CNBC's "Squawk Box".
The Chairman and CEO of Berkshire Hathaway refused to take a short position on Bitcoin.
"We don't own any, we're not short any, we'll never have a position in them," he said.
"I get into enough trouble with things I think I know something about", he said.
One Bitcoin is currently worth £10,460 ($19,623), according to CoinDesk.
It is up more than 1,500 per cent in the last 12 months despite a recent decline.
Bitcoins are generated by using an open-source computer program to solve complex math problems. This process is known as mining.
Last week the price increased by 13.5 per cent to £11,071 ($20,769) after a report found billionaire Peter Thiel, an early investor in Facebook and co-founder of Paypal, had heavily invested in the cryptocurrency.
Thiel's venture capital firm, Founders Fund, bought around £11 million - £14.7m ($20.6m to $27.5m) in Bitcoin in mid-2017, the report said.
Bitcoin bought by Thiel's firm are now believed to be worth hundreds of millions after the currency's surge last year.
Most mainstream investors have not bought large sums of Bitcoin over fears about cybersecurity and liquidity.
Buffett's cryptocurrency warning came as it was revealed he had set up two top lieutenants to one day take over his 56-year-old business empire Berkshire Hathaway.
He has given board seats to long-serving executives Gregory Abel and Ajit Jain, in a move that will see them take on responsibility for day-to-day running of the business.
Buffett said that one of the pair will eventually take over as chief executive of Berkshire – but insisted he has no plans to step down.
The 87-year-old said: "I will be as interested as ever, there's not a drop of Berkshire blood that's leaving my body.
"I'm at the office on Saturday every Saturday I'm home, unless there's something unusual going on.
"I couldn't have a better job than the one I have."
Asked if he might stay on for another decade, Buffett hinted that might be too long.
However, he stressed he remains in good health and does not intend to leave any time soon.
Indian-born Jain, 66, has worked for Berkshire since 1986 and runs its insurance businesses.
Buffett has lavished him with praise over the years, describing Jain's importance as "impossible to overstate".
The chief executive once said that if the pair were in a sinking boat together and shareholders could only save one of them, they should pick Jain.
He said that Jain and 55-year-old Abel, who runs Berkshire's energy businesses and has a reputation as a ferocious dealmaker, "would probably be under-described as world-class".
Although Jain has perhaps been feted more over the years, Wall Street consensus is that Abel will win the tussle because he is younger and his rival has such an irreplaceable grasp of the specialist, complex insurance industry.
Both men will now assume the title of vice chairman – the sale role held by Buffett's long-time business partner Charlie Munger, 94.
Although it sets the pair up for a protracted scrap over who will one day run the business, Buffett insisted he does not expect any trouble.
"There will be no horse race," he said.
"These two fellows know each other well, and they like each other.
"They're really of pretty equal importance."
