Volunteers spent Friday scrubbing gray paint off the mural that had been painted by French artist Pierre Roti for the Living Walls Conference.
"You can't just paint over something just because you don't like it," said Living Walls Director Monica Campana, adding she did not want the incident to dissuade other artists from taking part in the project.
Living Walls puts murals on walls of buildings in blighted neighborhoods in the Atlanta area.
The beautification effort by Roti irked some residents of southwest Atlanta. A group led by a former Georgia state lawmaker showed up this week and painted over the mural, which had been painted on a highway retaining wall, The Atlanta Journal-Constitution reported.
Atlanta's WSB-TV reported some people saw something sinister in the mural, which depicted snake- and fish-like fantasy creatures.
"The fishes were satanic. The scales were satanic," Angel Poventud told the TV station. "You know, they just don't feel that it represents their community."
Another group of volunteers gathered Friday with brushes and detergent and scrubbed much of the paint off with the help of Department of Transportation workers wielding power washers.