Restrict access to admin pages

On a MultiSite (MarketPress) installation I want to restrict access to some admin pages for site-admins. So let's say for example that I wanted to dis-allow access to edit.php?post_type=page. When an admin tries to visit that page, he is redirected to the dashboard. Any ideas on how to achieve this?
The admin_init action is for the whole administration interface, I'm looking for something a bit more specific, page/url-aware.