The Arc de Triomphe in central Paris was evacuated briefly on Tuesday after a bag of ammunition was discovered.
Police said metro lines in the area were also evacuated, as France reels from the killing of teacher Samuel Paty this month, continuing fallout from the Charlie Hebdo cartoons of the Prophet Mohammed, and a series of security alerts.
Police confirmed the discovery of a bag filled with ammunition and said the incident was initially treated as a bomb threat.
Two French news sites showed pictures of a blue bag with different kinds of ammunition.
There have been several false bomb alerts recently, including those at Lyon’s railway station last week and the Eiffel Tower a month ago.
France has warned its citizens in several Muslim-majority countries to take extra security precautions as anger has surged again over the cartoons, and the head of Russia's Chechnya region said Paris was pushing people towards terrorism.
Police continued to search the area around the Arc de Triomphe after the road reopened.
France has been on high alert since the beheading of Paty by an 18-year old Muslim man angry about the use of cartoons of the Prophet Mohammed in a civics lesson.
After the teacher was killed, more than 1,000 people gathered outside his school.
Paty's beheading was the second knife attack blamed on the cartoons since a trial started last month over the Charlie Hebdo killings in 2015, when 12 people were gunned down by militant attackers in and around the satirical magazine's Paris office.
Mr Macron has made sweeping proposals for battling extremism in French society, which will be presented to his Cabinet in December.
He has also defended free speech, which sparked a sporadic international campaign to ban French goods in some Muslim nations.
Al Qaeda-linked extremists have seized on the growing campaign to incite violence against the country’s political leadership.
