Under the planned budget unveiled by the European Commission, funding for farmers across the bloc via the politically sensitive Common Agricultural Policy (CAP) would fall by around five percent.
Paris has historically defended the single largest area of EU spending, a huge help to the politically influential but economically struggling French agricultural sector.
“Such a drastic, massive and blind cut is simply unimaginable,” a statement from the agriculture ministry said, adding that France “will not accept any decrease in direct income for farmers”.
The proposed reduction would create an “unprecedented risk” for French farms, it added.
French President Emmanuel Macron opened the door to changes to the CAP in a landmark speech on Europe in Paris last September 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 ministry said.
French farmers are the biggest beneficiaries from the CAP.
The draft budget was unveiled by European Commission chief Jean-Claude Juncker for the seven years after 2019 when Britain is expected to leave the 28-member European Union.
The proposals are the first stage in what promises to be hard-fought negotiations between the remaining members of the bloc.
The European Commission also risked a clash with eastern former Soviet-bloc countries such as Poland and Hungary over proposals to cut funds for states that violate democratic freedoms.
European Commission chief Jean-Claude Juncker insisted the budget plan for 2021-2027 was a “reasonable and responsible” way to fill a hole left by Britain's departure, and to fund new priorities including defence.
“We made a choice to go forward and that requires a modern, simplified more flexible budget,” Juncker told the European Parliament.
The departure of Britain, a net contributor, in 2019 leaves the bloc with what Juncker says is a 15-billion euro gap in its accounts.
EU Budget Commissioner Guenther Oettinger said countries would pay 1.114 percent of their annual gross domestic product under the plans, up from one percent in the current 2014-2020 multi-year budget worth 1.0 trillion euros.
The budget must be approved unanimously by all remaining 27 EU states, and by the European Parliament. Oettinger called for it to be agreed on by the time EU leaders hold their first post-Brexit summit in Romania in May 2019.
'Rule of law'
Meanwhile the European Commission proposed a seven-percent cut to so-called cohesion funds, the biggest beneficiaries of which are former Soviet bloc states in eastern Europe. It corrected an earlier figure of five percent.
Far more controversially, it also proposed for the first time to “suspend, reduce or restrict access” to funds for member states that breach the rule of law.
Warsaw, along with Budapest, has been at loggerheads with Brussels over democratic standards and their refusal to accept refugees.
Juncker said the commission is “proposing a new mechanism that will allow for the protection of the budget linked to risks arising from deficiencies in the rule of law.”
Poland reacted warily to the idea.
“There can be no space for arbitrariness,” Poland's deputy European affairs minister Konrad Szymanski said in a statement.
But Szymanski, reflecting his government's recent bid to resolve its two-year standoff with Brussels, said Warsaw did not see the proposals as “confrontational”.
Brussels wants to spend more on the digital economy, research, defence and protection for the bloc's borders against mass migration, including what one European source says is a quintupling of the border force Frontex to nearly 6,000 people.
Taxes on carbon emissions, plastic waste, and corporations could also contribute 22 billion euros annually, or 12 percent of total budget revenue, the commission said.