You mean for the English? It really depends on the context, but I think "I don't see" is better.I do not know why but "I can't see any children" sounds better to me.
A park (in American English at least) is a large area of grass and trees, especially inside an otherwise urban area. It may contain a playground, but not necessarily. A notable example is Central Park in New York.I know my question is kind of late but still. When you say "park" do you mean "playground"?