My suggestion is to rephrase in a positive way and demonstrate. For instance we say "no thank you, gentle touch only" and gently stroke DD's hand with an index finger. She may be enjoying the reaction she gets and thinking of this as a game. I would stop saying it hurts since it seems to egg her on. Try hard to remain calm, don't react, just gently take her hand and tell her what to do: "gentle touch only please". My DD is 2 now and she definitely experimented with hitting to get a reaction. Telling and showing her how to touch instead of reacting to the pain helped a lot and also curbed her biting habit (we said "gentle kisses only" for that.) I hope this helps, good luck!