On Friday Benalla was also taken in for question by police over the incident.
After a beat, Benalla appears back on camera, this time to attack a young man the police had already dragged a fair amount.
Also on Friday, prosecutors said Vincent Crase, a security aide for Macron's Republic on the Move party and an associate of Benalla's who also intervened during the May 1 protest, was also taken into custody.
The presidential palace added that Benalla had been suspended for two weeks after the incident came to light and had been transferred out of his role as security organiser for Macron's trips.
Roger-Petit said the punishment was the "most serious" ever given to a security director at the presidential Elysee Palace and served as a last warning before dismissal.
Macron, in the Dordogne region to officially launch a new postage stamp, didn't respond to questions about the scandal.
Mr Benalla still has an office in the presidential palace two-and-a-half months after the incident.
Asked about the video and the investigation during a visit to southwest France on Thursday, Macron refused to comment, saying only: "I'm here with the people".
Labour unions hold demonstrations every year on May Day in France, which often lead to police intervention.
'The day after the demonstration, I was informed by a colleague that Mr Benalla had been recognised in the field as being involved in law enforcement operations, and I saw the videos.
When the 21-year-old saw Benalla grab a woman by the neck and attack an already "neutralized" male protester, he made a decision to confront him on camera.
Le Monde newspaper published hte video showing Benalla striking and then stamping on a young man while wearing a police visor during a demonstration in central Paris on May 1.
Prime Minister Edouard Philippe, who denounced the "shocking images" in the video, said it was up to courts to decide on the matter. "As a result. the presidency has chose to start Alexandre Benalla's dismissal procedure", the official added.
Benalla now remains at the Elysee, but has been assigned to an administrative position where he deals with the security of organised events "inside the Palace", including recent World Cup celebrations.
Later the speaker of the lower house of parliament, Francois de Rugy, announced a parliamentary inquiry into the case.
"He caused an accident while acting as my driver and tried to flee the scene", Montebourg told Le Monde on Thursday.