Wilson - best known as Dwight from "The Office" - says the rope was placed in a tree in front of the home of his friend's sister, to be found by her 17-year-old daughter.
In his Instagram post, Wilson called the image "instantly chilling."
He says police shook off the racist gesture, essentially saying "What's the big deal?"
"What's the big deal? Well, officer, the noose is the symbol of lynching which was used to hang thousands of African Americans, especially by the Klan," Wilson wrote.
He did not identify in which city the incident occurred.