If it were me I am not sure. I think I would have a big problem with my neighbor who hit my kid instead of coming to me and letting me know. I don't feel as though a stranger has the right to put his hands on anyone let alone a child. I think I would have some seriously harsh words and depending on the situation yes I would press charges. Don't get me wrong the child would be punished by me and my husband not some neighbor dishing out corporal punishment.
I would not press charges, unless the child was injured. The kid antagonized the man. There was a time grabbing a kid and giving him a whack for being a little asshole was pretty normal. Not that I condone it, just saying I understand how the guy lost it.
They still have to live in the same neighborhood. It's not worth getting this guy in legal trouble and alienating all the neighbors. Besides, the man could turn around and charge the kid with trespassing.