Shares in commercial television group TF1 gained over 10 percent and those of M6 nearly 7 percent after the comments.
In the same news conference, he said France is not bankrupt, distancing himself from comments made last year by his prime minister, Francois Fillon.
"A country which has 15 percent of savings compared with its GDP (gross domestic product) is not bankrupt," Sarkozy told a news conference, noting that Fillon himself had subsequently modified his comments.
"But what is correct, and where he was right, is that a country which has been running a budget deficit for 26 years poses a problem."
End of 35-Hour Work Week
Sarkozy also said he hoped 2008 would mark the end of the 35-hour work week.
Asked during the news conference whether this was his wish, Sarkozy replied: "To say what I think, yes."
Past centre-right UMP governments have already introduced measures to undermine the 35-hour work week, which was introduced in 1998 when the opposition Socialists were in power.
Sarkozy in November announced plans to go further, for example by making some firms exempt from the 35-hour limit on working time in return for wage rises.
He also vowed to protect French businesses from sovereign wealth funds and private speculators and urged a state bank to roll up its sleeves and help France defend its industrial interests.
Sarkozy's appeal came months after a national row over the independence of the state-owned Caisse des Depots et Consignations, which manages state pensions and has answered directly to France's parliament since the aftermath of Napoleon.
"There is no question of France remaining unable to react in the face of a rise in the power of extremely aggressive sovereign funds which only follow economic logic," Sarkozy said.
"France must protect its companies and give them the means to develop and defend themselves. I want the CDC to be the instrument of this policy of defending and promoting the essential economic interests of the nation," he added.
- Reuters contributed to this report.