Brandy Miller, from Hoke County, North Carolina, said her daughter Caitlin was suspended for one day after she and her two friends were playing 'King and Queen' at her school, ABC affiliate WTVD reported.
In the game, Caitlin played a guard, protecting the royals, and picked up the "stick gun" to imitate shooting an intruder into the kingdom.
The Hoke County School system said Caitlin posed a threat to other students when she made a shooting motion - a violation of school policy, officials said.
"We know why it's bad. We watch the news, but then I have to tell my kid, 'you're not allowed to play like that in school because people do bad things to kids your age," Ms Miller was quoted as saying.
The Hoke County School school system defended its policy in a statement and said it would "not tolerate assaults, threats or harassment from any student."
"Any student engaging in such behaviour will be removed from the classroom or school environment for as long as is necessary to provide a safe and orderly environment for learning," the school system told the local TV station.
Caitlin returned from one-day suspension on Tuesday, but her mother said she was alienated by her friends and teachers over the incident.
She said she would like for the school to apologise to her daughter.