I won't be able to find the exact ordinance and I don't really care enough to search for it. I've heard from reliable sources and I witnessed firsthand that missionaries in New Zealand are not allowed to talk to kids. There are lots of missionaries, especially Mormons, so the rule is widely known.
"Missionaries are not allowed to talk to kids" is not the same as "preaching to kids is illegal." And the fact that you won't even look it up and are doing the "trust me, bro" thing makes me doubt even that is true.