The European Commission on Wednesday unveiled a draft budget under which funding for farmers across the bloc via the Common Agricultural Policy (CAP) would fall by around five percent.
That amounts to 365 billion euros over the 2021-2027 period.
France's agriculture ministry reacted with a statement saying the proposed reduction would create an "unprecedented risk" for French farms.
"Such a drastic, massive and blind cut is simply unimaginable," it quoted Agriculture and Food Minister Stéphane Travert as saying, adding that France "will not accept any decrease in direct income for farmers".
French farmers are the biggest beneficiaries from the CAP.
“The overall cut in the CAP budget is five percent and I regard this as a fair outcome to farmers, particularly given the challenging backdrop of a 12 billion-euros Brexit,” European Commissioner for Agriculture and Rural Development Phil Hogan told reporters.
In September French President Emmanuel Macron opened the door to changes to the CAP when he said it needed to be reformed.
The French government supports "a modernisation and a simplification of the CAP" which would protect farmers from price volatility as well as helping them adapt to and fight climate change.
The draft budget was presented by European Commission chief Jean-Claude Juncker to prepare for Brexit.
Overall, the 27 member states are facing a significant increase in their contributions for the next seven-year budget period which the European Commission wants to raise overall to 1,279 billion euros compared to 1,087 billions for the current period.
In January farmers iun south-west France staged protests over EU subsidy cuts.