A spokesman for Macron, who is currently riding high in the polls, has accused Moscow of being behind a flurry of cyberattacks on his campaign website and email servers over the past month.
“It's enough to see which candidates, Marine Le Pen or Francois Fillon, Russia expresses preference for in the French electoral campaign,” Foreign Minister Jean-Marc Ayrault said in an interview with Journal du Dimanche.
“Whereas Emmanuel Macron, who is pro-Europe, is being targeted by cyberattacks,” he added. “This form of interference in French democratic life is unacceptable and I denounce it.”
Le Pen, of the far-right National Front, is anti-immigration and anti-European Union, while Fillon is the conservative Republicans candidate who is pushing for closer ties with Moscow.
“Russia is the first to say that non-interference in domestic affairs is acardinal rule and I understand that. Well, France won't accept its choices being dictated to it either,” he added.
France warned Russia Wednesday against meddling in the elections, after a spokesman for Macron — the 39-year-old centrist former economy minister — pointed the finger of blame at Moscow.
The allegations come in the midst of a furore over Russia's alleged interference in the US electoral campaign that has forced out one of President Donald Trump's top aides.
US intelligence agencies had already accused Russian intelligence of hacking Democratic Party emails that embarrassed Trump's rival Hillary Clinton.
Earlier this week, Ayrault told French parliament: “After what happened inthe United States, it is our responsibility to take all steps necessary to ensure that the integrity of our democratic process is fully respected”.
German Chancellor Angela Merkel, whose country will hold a general election in September, has also voiced fears that Moscow could try to influence the vote through cyberattacks or disinformation.
A special meeting of the French Defense Council is planned next week to strengthen measures to protect against this kind of threat.