The woman also told the girl she would be given away to another family.
"Your actions on that day are incomprehensible ... not to mention potentially dangerous to all concerned," Judge Hobbs said.
The woman was sentenced to 150 hours' community work and nine months' supervision.
The girl is now staying with other family.
The woman and her partner, 27, were accused of giving a rifle to the girl after she approached her mother claiming the man assaulted her on February 5.
The claim was not believed by the mother.
Instead, the couple allegedly gave the girl a rifle and told her that if she was telling the truth then she should shoot the man.