How do I respectfully tell someone to NOT cc my manager when they send me an email over trivial things?

People in this office have a bad habit of thinking that every time they ask me for something trivial or have a small piece of feedback to give me, they need to cc my manager. I'm looking for some mature, knowledgeable advice on how to reply back to the email letting them know i don't appreciate the attempt to sandbag me. If someone has feedback for me over something trivial, they should talk to me about it first.