So when you're friends with people on Facebook, they can still leave comments on posts that you make to your own page. In the security preferences on Facebook you can restrict certain people from seeing the post itself. The general options you can see are 'public' 'friends of friends' or 'friends only'. However, through your friends list on your profile you can further separate people into specific categories like 'Co-Workers' or 'Family' and then when you make a new post, you can choose from the top-down selection in 'Who Can See This?' you can decide which audience you want to see that specific post.
Facebook currently does not have a blanket option to restrict comments altogether on posts that you make. The best you can do it restrict who sees the post, because if they can't see it, they can't comment on it.