Labour leader Ed Miliband warned the Deputy Prime Minister after reports suggested he was supporting a move by Iain Duncan Smith, the Work and Pensions Secretary, for a reconsideration of the policy to give all pensioners, including the better off, free TV licences, prescriptions and bus passes, as well as the winter fuel allowances.
It is thought that Mr Duncan Smith wants to look again at who is eligible for the free benefits because he needs to reduce the welfare bill still further.
Cuts to free TV licences and prescriptions for the better-off pensioners could save the UK Government £5 billion.
A Liberal Democrat source commented about Mr Clegg's view: "If you're faced with helping the wealthiest pensioners or helping the vulnerable across Britain, then his priority is the vulnerable people across the country who need the help most."
However, David Cameron is said to be insistent that there will be no means-testing, and he is determined to stick to the pledge he gave at the last General Election when he assured voters that such benefits would be maintained under a Conservative government.
Mr Miliband said: "In the end, this is a question of political trust.
"The Prime Minister made a promise at the election about this and looked the camera straight in the eye and said it's total nonsense: we are not going do anything about this.
"Let's see what happens."