bad parenting

last night i yelled at a toddler i don't know.  

let me set the scene for you: a crowded kid-friendly restaurant on a saturday evening, the kid area has a play house and all ages of kids are playing and getting a bit crazy because they're having so much fun.  my 22-month-old was going in and out through the playhouse door, enjoying the open and close action and not really interacting with any other kids directly.  then one time she opened the door to go back inside the house, and a little girl who was inside (who was only slightly bigger, and probably was very close in age because my daughter is on the small side) was standing there.  and then she punched my daughter with a closed fist in the neck/chest a couple of times. i scooped up my daughter while blurting out "what the hell is wrong with you?!".

i am really embarrassed.  fortunately, i spoke in english and i live in a non-english-speaking country.  i had never been in the situation before, and i honestly don't know what i would have said if i were in an english-speaking environment.  i like to think i would have said "there is no reason for hitting!" or something along those lines.  but i honestly don't know.  i should have prepared myself for that months ago, but i just didn't.  and i feel awful.  thank goodness the little girl couldn't understand me. my temper was a little frayed because i had just cleaned up a crazy amount of shit in the bathroom (in the restaurant we had the first poo-in-pants accident since we started potty training and instead of remaining calm when i was trying to delicately peel off her pants so that the poo would fall nicely into the toilet, she panicked.  poo went all over the toilet seat, on the back of the toilet, on the floor, on her shoe, etc), but that is no excuse. today i have been practicing simply responding with a firm 'no!' in czech and i hope i'm ready to act like an adult next time.

but here is my question: what do i say to my daughter? i don't want her to hit back. i would like her to be comfortable getting out of violent situations even if she is mad. what should i tell her so she will have the appropriate script in her head?