Richard Ferrand, secretary-general of Macron's En Marche! (Onwards!) party, said that Russian state-controlled media Russia Today and Sputnik had spread false reports with the aim of swinging public opinion against Macron.
An independent centrist, Macron has surged in campaigning for the French election and opinion polls make him favorite to win election in May.
Ferrand said that Macron, as a staunch pro-European, was a Russian target because he wanted a strong united Europe that had a major role to play in world affairs, including in the face of Moscow.
Sputnik earlier this month ran an interview with a conservative French lawmaker accusing Macron, a former investment banker, of being an agent of "the big American banking system", a report that was in turn picked up by Russia Today.
"Two big media outlets belonging to the Russian state Russia Today and Sputnik spread fake news on a daily basis, and then they are picked up, quoted and influence the democratic (process)," Ferrand said.
Russian newspaper Izvestia has also reported comments from Wikileaks founder Julian Assange who said his organization had "interesting information" about Macron, who opinion polls say would easily beat far-right leader Marine Le Pen in a May 7 runoff.
In addition, Ferrand said the Macron campaign was being hit by "hundreds if not thousands" of attacks probing the campaign's computer systems from locations inside Russia.
Calling for government action to prevent foreign meddling in the election campaigning, Ferrand said: "What we want is for authorities at the highest level to take the matter in hand to guarantee that there is no foreign meddling in our democracy. The Americans saw it but it came to late."
U.S. intelligence agencies said in a report last month that Russian President Vladimir Putin had directed a cyber campaign to help Republican Donald Trump's electoral chances by discrediting Democrat Hillary Clinton in the 2016 presidential campaign.
French Defense Minister Jean Yves Le Drian promised last month to boost military resources to fight foreign cyber attacks,
acknowledging that France was no less vulnerable than the United States.
In an election campaign which has sunk into smear and sleaze, Macron on Feb. 7 was also forced to kill rumors of a gay relationship outside his marriage to Brigitte Trogneux.
The media reports about Macron emerged from Russia as erstwhile poll favorite Francois Fillon, a conservative who speaks positively of Putin, was hit by a scandal which has badly affected his election chances.
He has seen his poll lead evaporate following French press allegations that his wife had been paid for being his parliamentary assistant without doing any real work.
Fillon's decline has put Macron in a position to make it into a May 7 runoff vote, where polls see him winning by a large margin against far right leader Marine Le Pen, who has received funds in the past from a Russian lender and pledged to have good relations with Russia if elected.