The woman was reportedly attacked on Monday, the first day of the Muslim fasting month of Ramadan, in a bar in central Nice.
"I was all alone in the bar when two passersby barged in," she told the Nouvel Obs newspaper.
"They pointed their fingers at the bottles of alcohol that they saw behind the counter, then one of them said to me in Arabic 'You should be ashamed to be serving beer during Ramadan'
One of the men then added: "If I was God, I would have you hanged."
After some heated words between the trio, the men left, but one returned soon after to hit the woman in the face, knocking her to the ground. She was left with bruises on her face.
The entire exchange was caught on CCTV cameras, reported the paper, which had seen the footage.
The attack has since been reported to authorities, and the tape has been handed over to police.
The victim said she was shocked that such an attack could take place in France.
"Serving alcohol doesn't mean I'm not following my duties. I'm doing it because I am a barmaid. In Tunisia, I do the same job and I never had the same problem. I can't believe that in France, the country of liberty, that I could be attacked like this," she said.
The men have been identified, but are yet to be arrested, Nouvel Obs reported.
The city of Nice was plagued by similar news in 2014, when a bakery was vandalized because the owner was considered to be a "bad Muslim" for selling food containing pork.