The Pittsburgh Post-Gazette reported that the 24-year-old Davis uploaded a video to Snapchat of the teen working at a Chick-fil-A drive-thru in Cranberry Township, located about 20 miles north of Pittsburgh. Davis is heard saying, "This kid like 8 years old. No wonder the lines be so long."
An attorney who represents the family said their son didn't know about the video until he was bullied at school afterward.
The lawsuit filed Friday includes claims of libel and cyberbullying, and it seeks an unspecified amount in damages. It says the teen has suffered from headaches, depression, sleeplessness and anxiety.
Eugene Lee, the CEO of MBK Sports Management, called the lawsuit frivolous. He said Davis did not intend to demean the teen.
"Sean Davis is an exceptional young man of strong character, integrity and faith," Lee said in a statement. "We stand by him and fully support him in the midst of these baseless claims."
The Associated Press contributed to this report.