"The French must save to become more capable of acting. They must of course also make economic reforms," Michael Fuchs, deputy chairman of the Christian Democrats' parliamentary group told public radio.
"They must change the working hours. You know that the French still have the 35-hour week. That can't work when in Switzerland people work 42 hours, in Germany 40 hours," he complained on Deutschlandfunk radio.
He was speaking before the European Commission announced that France's public deficit was set to be worse than expected in 2013 and 2014, veering up to 3.7 percent of output this year and 3.9 percent next year.
The EU sets a ceiling of 3.0 percent of output.
France's wages and work ethic have been under the international spotlight this week after the head of US tyremaker Titan, Maurice Taylor, mocked French workers for putting in only "three hours" a day, prompting a sharp retort from Paris.
Fuchs also criticised France on its pensions policy. "It's simply necessary for people to work longer. You cannot retire at 60, that doesn't work any more. The French must consider that," he added.
"Unfortunately France is a problem child in the euro, since other countries have done their homework substantially more intensively. Spain, also Italy under (outgoing Premier Mario) Monti...," he said.
"The whole eurozone must be internationally competitive. And there, the French are far behind."
Asked to comment on France's public deficit, Merkel's spokesman Steffen Seibert said it was not for the German government to assess but that states must do their homework to win back confidence in Europe.
"The chancellor has always made clear that in her opinion the crisis is not over. We have achieved much... There is still much to achieve," Seibert told a regular government news conference.