Ken Clarke has told Tory eurosceptics not to expect powers to be grabbed back from the EU at this week's summit.
The justice secretary said the prime minister should concentrate on resolving the eurozone crisis.
David Cameron has said he will not sign any reworked EU treaty designed to solve the crisis if it does not contain safeguards for UK interests.
There have been calls for a new treaty to achieve greater integration of the 17 eurozone states.
But that would require the agreement of all 27 members, including the UK.
The pro-EU Mr Clarke in an interview with the Financial Times said it would be a distraction to open up discussions about the "wider structures of the union".
"We're not going to renegotiate any transfers of powers, in my opinion," he said.
Britain should be prepared to accept "proper" financial regulation from Brussels, he went on. But he rejected the idea of an EU "Tobin tax" on financial transactions.
"It's the devil's own job to collect," he said, and added that New York and Hong Kong would not follow suit.
The prime minister says he will seek to return powers to the UK at the right time but many Conservative MPs want him to go further.
In an article for the Times, Mr Cameron wrote that the 17 eurozone countries could decide to reach agreement on their own, but "Our colleagues in the EU need to know that we will not agree to a treaty change that fails to protect our interests."
Some observers have argued that a treaty of 17 states "would be more effective if it had access to the institutions of the EU such as the European Court of Justice and the Commission," the article says.
"These institutions belong to all EU states and their use outside the treaty would clearly require safeguards."
David Cameron says he will go to Brussels to "defend and promote British interests"
"Our asks will be practical and focused. But eurozone countries should not mistake this for any lack of steel."
The UK's priorities are protection for the single market and the UK financial services sector.
Germany and France are developing a plan for greater fiscal integration among the eurozone's 17 members ahead of a crucial meeting on Friday.
Downing Street has said that none of the proposed changes being discussed would trigger a referendum in the UK as they would not constitute a significant transfer of power from Westminster to Brussels.
The measures under consideration were about how the eurozone countries organised and governed themselves, it has claimed.
But many MPs say an agreement involving just the 17 members of the eurozone would alter relations with the EU as a whole and a referendum was needed.
The last Labour Foreign Secretary, David Miliband, has said tough talk by the prime minister could lead to less influence.
"David Cameron faces a real trap from those in his own party who are spoiling for a fight that would bring Britain out of the European Union," he said.
"The trap is that in the end the other countries will go ahead on their own and not just decide economic policy for the eurozone, they'll end up designing policy for the whole of the European Union.
"And that will put Britain in the second division, a place that it's tried to avoid for the last 40 years."
Last month, more than 80 Tory MPs defied the government and called for a referendum on the UK's membership of the EU.