Mr Denham, who is the Parliamentary aide to Labour leader Ed Miliband, insisted the party did "not absolutely rule out" a definitive poll. Mr Miliband had appeared to draw a clear dividing line with the Conservatives during Prime Minister's Questions, telling the Commons that his party "do not want an in/out referendum".
However, Mr Denham then told the Daily Echo there had been "a bit of over-interpretation" of Mr Miliband's comments.
He said: "We do not absolutely rule it out in the future, we do not know what issues will come up in the future.
"But we think to call one now will damage and destabilise the economy."
His Labour colleague, Alan Whitehead, echoed the criticism of David Cameron's decision to commit the party to holding an in/out referendum by the end of 2017, once he has tried to negotiate the return of some powers to Westminster.
Dr Whitehead, the MP for Southampton Test, said it was "folly" to make such a pledge so far in advance.
However, Mr Cameron's promise, in a speech in London this morning, was welcomed by Conservative MPs who cheered their leader to his seat at Prime Minister's Questions.
They accused Labour of being unclear on its support for a referendum.
"It put Ed Miliband very much on the back foot."
She said she had received "many hundreds" of letters from constituents calling for a referendum, and said "the jury is still out" on how she would vote.
Daniel Hannan, Eurosceptic MEP for the South East, said it had been "an extraordinary moment".
He added: "critically, the people who decide whether it's a good enough deal won't be the ministers and mandarins who have brought us to our present unhappy state, but the electorate as a whole.2 But the Prime Minister was heavily criticised by a Liberal Democrat, South East MEP Catherine Bearder.
She said: "David Cameron's speech was plagued with confusion - confusion over who it is was aimed at, and confusion over what he really wants to achieve.
"His increasingly desperate pledge to push for a positive vision for the EU is at odds with his attempt to appease chunks of his own party.
"Mr Cameron has doffed his cap to the right wing nationalists in the Tory party, whose real agenda is an immediate exit, and simultaneously put British growth, jobs and investment at risk."