"I've got nothing against foreigners but I say to them: if you come to our country, don't expect that you will be taken care of, treated (by the health system) and that your children will be educated for free," Le Pen said.
"That's finished now, it's the end of playtime," she told an audience at a conference organised by a polling group in Paris.
Opinion polls suggest the leader of the National Front (FN) will finish second in next year's presidential election but she is hoping for new momentum after Donald Trump's victory in the United States.
Such a move would contravene current French law which guarantees school places for all children.
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She also said that any foreigner using the public education system without paying tax in France would have to contribute.
"We're going to reserve our efforts and our national solidarity for the most humble, the most modest and the most poor among us," Le Pen told the conference.
The staunchly nationalist FN sees itself as part of a global revolt against immigration, established political parties and globalisation epitomised by Trump's victory last month.
Le Pen falsely claimed on today that anyone aged over 65 could arrive in France and start claiming old-age social security payments.
Polls currently show her qualifying for the second-round of May's election where she is forecast to face - and be defeated by - rightwing Republicans party candidate Francois Fillon.
Few analysts see her as likely to take power, but it has been an unpredictable year in politics and France's sickly economy and immigration are top issues for voters.