Cameron: Rich will help cut deficit
But the Prime Minister and Chancellor rejected Liberal Democrat proposals for a "mansion tax" on expensive properties and benefit cuts for wealthy pensioners.
Speaking as the Conservatives' annual conference opened in Birmingham, Mr Cameron also confirmed that the Government is considering action to prevent new waves of European migrants coming to the UK to work - something which could put the UK on collision course with EU rules on freedom of movement.
With Tories trailing in the polls and Labour's Ed Miliband enjoying a boost following his well-received "One Nation" speech last week, Mr Cameron and Mr Osborne kicked off the conference with a raft of initiatives designed to win back control of the political agenda.
The conference was set to be dominated by the economy, with Mr Cameron saying his party would "level" with the public about the need for another £16 billion of spending cuts in 2015-16.
"We have to find these spending reductions and if we want to avoid cuts in things like hospitals and schools, services that we all rely on, we have to look at things like the welfare budget," he told BBC1's Andrew Marr Show.
Mr Cameron made clear he did not anticipate an in-or-out referendum on British membership of the European Union. And he dismissed the prospect of voters deserting the Tories for the UK Independence Party in the hope of securing an in/out vote, saying: "I think Ukip is a complete waste of time, obviously."
Ukip leader Nigel Farage responded: "Since Cameron has become leader, membership of the Tory Party has halved. Since he last abused Ukip, our poll ratings have doubled. The Prime Minister is once again showing his legendary lofty disdain for ordinary voters."
Labour's shadow Cabinet Office minister Michael Dugher said: "Britain needs a 'One Nation' Prime Minister to deliver real change. Instead we've got one that asks millions to pay more and millionaires to pay less."
© 2012 Press Association