In a warning to the Prime Minister, Mr Clegg suggested the Liberal Democrats will not go into Coalition with a party that wants a re-negotiation with Europe.
"We should always be governed by what’s in the national interest, and my view is that years and years of uncertainty because of a protracted, ill-defined renegotiation of our place in Europe is not in the national interest because it hits growth and jobs," he told Sky News.
The Deputy Prime Minister said there is a "right time and there is a right place for a referendum" but criticised Mr Cameron's decision to name a date in a landmark speech this morning.
Mr Cameron pledged an in-out referendum in the first half of the next parliament, arguing that democratic consent for membership is currently "wafer thin".
However, the Liberal Democrat leader said people would prefer the Coalition to focus on creating jobs and economic growth.
He said the Prime Minister can promise whatever he likes when speaking only for the Conservative Party.
"It’s entirely for the Prime Minister as leader of the Conservative Party to set out what he wants to put in the Conservative Party manifesto and what he wants to do if there was a Conservative majority government," he said.
"My priority remains, and will always remain: yes, reform in Europe; yes, a referendum where the circumstances are right, as we’ve set out in law; but above and beyond anything else, promoting growth and jobs and building a stronger economy in a fairer society."
Mr Clegg echoed Labour in his accusation that the Prime Minister's plan is "not in the national interest".
The opposition party has accused Mr Cameron of appeasing Eurosceptic backbenchers, rather than doing what is right for Britain.
"I think that many people, including many people in Brussels.. I think they will regard this speech as much more unvarnished, much more unqualified than they were expecting, but also unworkable," he told the BBC this mornign.
"I think other member states will not negotiate such a new settlement as the special state for Britain wihtin the European Union. I don't think they will provide a new treaty to accommodate Britain's demands and I don't think they will agree a timetable for negotiation that suits Britain's
Rowena Mason, Telegraph.co.uk