Former President Francois Hollande's government had predicted 2.8 percent earlier this year, which would have respected the European Union target for the first time in a decade.
However, TF1 said that national audit officials, who will publish a review of estimates on Thursday, anticipated the deficit would be at 3.2 percent in 2017.
"We shall see on Thursday," Finance Minister Bruno Le Maire told the broadcaster's evening news bulletin. "The only thing I can confirm is that if we don't do anything before the end of the year, then we will not meet our European commitments."
Le Maire said there would have to be public expenditure cuts ranging from the state and local government to social services.
"France has been drugged by public spending. We have to reduce public spending because it's a question of national sovereignty," he said. "We ... will make a number of proposals concerning all public spending."
(Reporting by John Irish and Sophie Louet; editing by Mark Heinrich)