The campaign comes two weeks after police say a man dressed as Spider-Man slugged a police officer who told him to stop harassing a tourist for a bigger tip.
The department is handing out fliers with the reminder in red boxes superimposed on black-and-white photograph of Times Square's versions of Mickey Mouse and Elmo.
The fliers instruct people to talk to a police officer or call 911 if a character gets out of hand.
Police Commissioner William Bratton has referred to the characters' wild behavior as Times Square's "Elmo issues."
In the last two years, a man dressed as Cookie Monster was charged with shoving a 2-year-old, a person attired in Super Mario's overalls was accused of groping a woman and an Elmo figure pleaded guilty to disorderly conduct after unleashing an anti-Semitic tirade.
City Council is considering requiring licenses and background checks for costumed performers but copyright issues have held up final approval, since most of the costume wearers are not authorized by the characters' owners.
Mayor Bill de Blasio endorsed the licensing plan, saying the characters had "gone too far."
Even those dressed as superheroes, he said, have to "play by the rules or you won't be working here any longer."