Emmanuel Macron was struck by a small projectile — believed to be an egg — while surrounded by press and members of the public in Lyon.
The object struck the French president on the side of the face before bouncing away during a visit to the Eurexpo convention centre.
According to Lyon Mag, whose reporters filmed the incident, the young man who threw the object made a gesture of protest and shouted "vive la révolution". He can be seen being placed in handcuffs by security services in their video.
Lyon Mag also report that Mr Macron asked his team if he could meet the young man who threw the egg to understand his reason for doing so.
The president had been attending Sirha Lyon, a meeting of food service and hospitality leaders in the city in south east France.
There he made a series of announcements of policies aimed at trying to revive the restaurant and hotel sectors, including a tax exemption for tips paid on bank cards.
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