In a video circulating on social media, President Macron is seen walking up to a barrier on a trip to Tain-l’Hermitage outside the city of Valence. He was on an official visit to the south-east of France.
A man in a green T-shirt slaps Mr Macron in the face before officers quickly move in. The two men have been arrested following the incident, French media report.
“We must not let ultra-violent people take over the public debate: they do not deserve it.” said Macron.
The man reportedly cried “Montjoie, Saint-Denis” – the battle-cry of the old Kingdom of France.
Mr Macron briefly returned to the barrier after the incident and once again interacted with the crowd. He said, “I continued and I will continue, Nothing will stop me.”
As yet the identity and motive of the man are unclear. The local prefecture said he and another individual are being questioned by the gendarmerie, in a statement reported by AFP news agency.
Officers were out in force on the streets of Valence shortly after the slap, according to one French journalist’s tweet.