In a letter to the profession, the British Medical Association (BMA) said pension contribution hikes are "unfair".
GPs have been urged to press the government for a "fairer" deal, as they face paying 13% of their salary into the NHS pension scheme, up from 10.9% last year.
BMA council chair Mark Porter said: "We know doctors still feel let down by the NHS pension changes.
"This is their opportunity to help demonstrate to the government that it remains an issue that matters, and one where a fairer deal can and should be achieved."
The BMA has urged GPs to take part in a consultation on the increased contribution rates.
Health Secretary Jeremy Hunt asked the BMA to make a recommendation on how pension contributions should be tiered.
The consultation ends on 12 February 2013.