Speaking to the Labour party conference in Manchester last week, Mr Burnham said Mr Cameron must 'put these dangerous plans on hold' and 'give the NHS the stability it needs'.
'If you don't, get ready for the fight of your life - and the public will be on our side, not yours,'
he said. The tub-thumping speech came as the union Unison secured a date to begin legal proceedings against health secretary Andrew Lansley.
The union claims Mr Lansley is initiating his sweeping White Paper reforms before there has been adequate consultation.
From 14 October the union will attend a court hearing to argue for a judicial review against the health secretary.
Representatives from rival union Unite told the Labour conference the White Paper was 'the biggest onslaught on the health service since 1948'.
Mr Burnham said the coalition government had 'no mandate' for the 'break-up of a successful NHS'.
'We have GPs wondering when they signed up to become the managers of markets and multi-million pound budgets.
'Patients aren't asking for it. GPs and NHS staff don't want it. The public did not vote for it. People will not forgive you for it,' he said.
Mr Burnham said the government had performed an 'epic U-turn' since its post-election promise of 'no more top-down reforms of the NHS'.
'It is nothing short of scandalous to spend up to £3 billion on a political experiment with our NHS at a time when every single penny is needed to maintain jobs and standards of patient care,' Mr Burnham said.