The man was watching a softball game with friends in Lakeland, Florida, over the weekend when he noticed a 2-year-old girl walking around the sports complex alone, according to a statement from the Lakeland Police Department.
Concerned, the man approached the girl and walked with her in an attempt to locate her parents.
One independent witness confirmed this to authorities, according to the police incident report.
The parents of the girl were told that their daughter had been seen with the man, walking towards a playground, police said. The parents believed that their daughter was being kidnapped.
Sgt. Gary Gross of the Lakeland Police Department told CNN that the girl's father and some of his friends took the girl and attacked the man.
"They grabbed that child and took him from behind and knocked him to the ground and started kicking and hitting him," Gross said.
Lakeland police said in their statement that "this incident truly involved a good Samaritan trying to assist a lost child finding their parents."
Family spread man's information over Facebook
The man who was beaten signed a waiver of prosecution, Gross said, saying he wouldn't bring charges against the father. "He's a parent of two daughters so he could understand how they reacted."
When the police told the girl's family that the man wouldn't be arrested, they reported the father "became increasingly agitated."
"So I guess in Lakeland, you can kidnap a child and get away with it," the father said to police.
Unsatisfied, the family took to Facebook and shared his name, his profile and pictures of him and his kids, calling him a sexual predator. Soon, his information was everywhere.
One Facebook post, provided to CNN by the Lakeland police, included the man's picture and warned people in the area to look out for him. The author accused him of trying to take the girl.
"I can only imagine the fear that was in them but I'm so glad they were able to act fast and keep their little girl from being taken," the post said. "Let's make him go around on here to help keep all babies safe from this piece of s***."
Gross said the posts suggested that people band together to run the man out of town. They never got the chance.
The man and his family left town of their own accord, afraid for their lives after receiving threats.
According to Gross, the father of the little girl hasn't expressed any remorse for attacking the good Samaritan. "They still think their daughter was trying to be kidnapped," he said. "They're just not listening."
Police: Be careful what you post
Lakeland police warned people that the Facebook post contained "false information and speculation."
"Be careful about what you post on social media so as not to victimize an innocent person," the department said.
"Before posting information on matters such as this, we encourage people to identify the source and the validity of such claims before sharing them."
Only one person called the police department "to get the correct information," the police said.
Gross told CNN he's spoken with the man since the incident, who understands how his actions could have been misinterpreted. But he stands by them.
"He said if he had to do it all over again, he'd do the same thing," he said.