Duffy, 20, made 19 appearances for Scunthorpe last season, scoring once, but Moore says the Everton youngster is not a target.
Rovers were beaten 3-1 by Bolton in a pre-season friendly on Tuesday. Moore was upset with the way his team defended, but wants to bring in someone with more experience.
"You can see where we're short. The defensive part is not good at the moment," he told Tranmere's official website.
"We could probably get an 18 or 19-year-old kid who will come in and make the same mistakes we're making now.
"We don't want to bring in a young lad who is going to learn the game if we can help it. But we'll keep knocking and hopefully that will change."