Protesters with signs stating “save our kids” congregated outside the Esso filling station in Cowdenbeath.
A group of around 30 people was at the garage in High Street on Friday morning, with some pupils joining the group at lunchtime.
They told The Courier they were protesting because Muhammed Shahbaz, who is on the sex offenders register, worked at the premises.
The owners made it clear Mr Shahbaz no longer works at the garage.
Mr Shahbaz was jailed for two years in 2011 for a series of indecent assaults on teenage girls he had illegally sold alcohol to.
Speaking on behalf of the campaigners, Joe Lowther, 31, said: “We just want to protect our kids and protect our community from this.”
The gathering was organised on the social networking site Facebook. Mr Lowther said many more local people were behind the campaign.
“There’s going to be more coming down after work and also children coming down to have a peaceful protest after school.
“People have gone in and filled up with fuel. We’re not stopping people using the garage.”
Some protesters were holding banners with the message: “Ask why we’re here.” One said: “This is just the start of it.”
Local sources said Mr Shahbaz owned the business but Sheraz Amin, who was working at the petrol station, said the business was owned by his wife. He said Mr Shahbaz was a family friend who had worked at the shop, but only on weekends.
“People have the right to protest, but they shouldn’t do things that are harmful to my business or my wife’s business,” he said.
“He doesn’t work here any more. Mr Shahbaz has nothing to do with the business. He will never come back to the site, no chance at all.”
Mr Amin told customers the protest was the result of an “employee dispute”.
A spokesman for Police Scotland said: “A number of police officers attended a demonstration in Cowdenbeath to facilitate a peaceful demonstration and ensure public safety.”
Photo by David Wardle