The LibDem MP said the consequences would be incalculable and there was "no automatic guarantee" Europe would not disintegrate into conflict.
His comments came after a Sunday newspaper reported Education Secretary Michael Gove believes Brussels should be told: "Give us back our sovereignty or we will walk out."
Mr Gove, a close confidant of Prime Minister David Cameron, reportedly said he would vote to quit the EU if there was an immediate referendum on Britain's membership.
Mr Cable said: "I think we need to take stock that if the eurozone were to unravel in a way that destroyed the European project – and there is a risk that could happen – the consequences would be absolutely incalculable.
"We tend to forget, until we were reminded last week of that Nobel Prize, the European project was constructed in order to rescue Europe from extreme nationalism and conflict. There is no automatic guarantee that won't return."
His comments came during a discussion on the austerity measures, and the euro, at the Cheltenham Literary Festival. The senior minister said Britain would suffer if the currency was not maintained.
He added: "We are not in the eurozone so we cannot directly influence it. We will be heard very loudly if it does unravel
"My sense is that the Germans in particular realise how much is at stake. A series of sensible measures has been taken in recent months.
"I think deep down there is enough common sense and a sense of survival to prevent this getting out of control."
Meanwhile, Defence Secretary Philip Hammond said the reports about Mr Gove's alleged comments highlighted a hardening of attitudes in the Cabinet.
"The point that Michael is reflecting – and many of us feel – is that we are not satisfied with the current relationship," Mr Hammond told BBC1's Andrew Marr Show.
"The mood has changed... because for the first time in a decade, those of us who are uncomfortable with the way that relationship has developed see an opportunity to renegotiate it. It makes sense for Britain to be in the single market, but to reset the relationship."
l Mr Cable also criticised the banks for becoming "over-conservative" in the wake of the financial crisis.
