A motion approved at the LMCs conference in Liverpool on Tuesday asserted that 'the primary moral, ethical and professional duty of a GP is to the patient whose care they are managing'.
It comes less than a week after Mr Lansley told a NICE conference in Birmingham that practices and clinical commissioning groups (CCGs) must consider how individual treatment costs affect all patients to preserve the NHS as free at the point of use.
The motion, passed by majority, also called on the government to be honest with the public about NHS resources being limited.
The motion also 'deplored the fact that the government wastes billions without a political mandate on the unnecessary reorganisation of NHS structures and bureaucracy'.
Representatives agreed that the BMA should 'deplore the government's waste of public funding on unfounded initiatives and policies that do not deliver a defined outcome that benefits patients care'.
Dr Shaun Millns-Sizer of Bradford and Airedale LMC proposed the motion. 'Billions will be wasted on NHS reorganisation on apparently the government's whim,' he said. 'The risk is that patient relationship is close to divorce.'
Dr Kishor Vasant of Southwark LMC, also speaking in favour of the motion, said: 'Rationing has been a fact in the NHS for a long time, but successive governments have been coy about using the term.
'It's time the government promoted open debate about limited resources and involved patients in the debate.'