Jean-Luc Mélenchon Tweets attack after German leader asked France for more budget tightening; German minister strikes softer tone.
French president has 100 days to deliver on changes after EU set a deadline for removing barriers to growth by March 2015.
After meeting in Berlin, French and German economy and finance ministers pledged to present public investment plans in December.
President Hollande urged EU to ease rules on budget discipline to protect flagging growth ahead of full summit later this month.
Brussels may be willing to use new compliance rules to tell Paris to rewrite its 2015 budget, triggering a crisis.
Ministers say borrowing will meet EU limits two years later than promised and that 'no further effort will be demanded of the French'.
Heath minister Marisol Touraine says social security deficit will hit 11.7 billion euros this year instead of originally forecast of 9.8 billion.
Ministers from countries who have carried out major budget cuts said to be 'very unhappy' with French failure to meet deadlines.
Arnaud Montebourg, an outspoken critic of austerity, also attacked EU policies and said European Central Bank should do more to help growth.
Organisation also fears voter resistance to spending restraints could jeopardise France's long-term strategy for restoring public accounts to health.
But French finance minister Michel Sapin insisted in a statement that Paris would meet the 3 percent target in 2015.
Spelling out measures which angered sections of his own party, new prime minister Manuel Valls said: 'We cannot live beyond our means.'
The latest European Commission economic forecasts say the French government deficit will hit 4.1 percent this year, 3.8 percent next year.
Finance minister Pierre Moscovici said 2013 public deficit will come in at 4.1 percent of GDP, higher than the 3.9 percent agreed with EU.