The court said in a statement that law enforcement agencies in France had enough other resources to monitor websites which incited militancy, and people who clearly had “a terrorist intention”.
Though the presidency seems to be slipping from his grasp, Fillon, a 62-year-old former prime minister, manages to stem rebellion in his Republicans party.
“If you’re told I lead a double life with Mr Gallet it’s because my hologram has escaped,” Emmanuel Macron told supporters at a rally.
Charge against Sarkozy, who led France for five years from 2007, exposes the 62-year old conservative politician to a one-year prison sentence if convicted.
Le Pen and her party are facing their own scandals, including one over assistants in the European Parliament and investigations over her 2012 campaign financing.
Fillon denied wrongdoing after Le Canard Enchaine newspaper reported the former prime minister had paid his wife hundreds of thousands of euros for work she may not have done.
Marine Le Pen, locked in tight three-way race to succeed Francois Hollande this spring, said she would not “submit to persecution” by paying the money back.
Francois Fillon and his wife are being questioned by investigators as part of a probe into allegations that Penelope Fillon was paid for fake jobs.
Hollande said, “We have to stand together in Europe. What is at stake is populism. The kind of discourse now coming from United States encourages populism and even extremism.”