French President Emmanuel Macron was shaking hands in southern France Tuesday when a man shouted "Down with Macronia" and slapped him the face.
He could also be heard on video shouting the battle cry of the French army when the country was still a monarchy.
Two of Macron's security detail tackled the man in the T-shirt, and another ushered Macron away. But the president, a few seconds later, returned to the line of onlookers and resumed shaking hands.
Macron later said he had not feared for his safety, and that nothing would stop him carrying on with his job.
Two people were arrested, a police source told Reuters. The identity of the man who slapped Macron, and his motives, were unclear.
French Prime Minister Jean Castex condemned the incident in a speech at the National Assembly.
"I am completely in solidarity, because by targeting the head of state, it's quite simply democracy that is being targeted."
Macron was on a visit to the Drome region to meet restaurateurs and students and talk about returning to a normal life after the COVID-19 pandemic.