Create role for changing user accounts and not admins I am developing a documentation site for a client. The site has the option of Who can register accounts? set to  Visitors, but administrator approval is required.
So, currently only Admin(user1) is doing the user approval procedure.  

Our client has a customer services team which handles this account approval procedure currently. So, if I create a new role (say moderator) and give it permission to administer users (blocking/unblocking, changing role of a particular user), then they will also be able to modify admin users' account; and this is not expected.  

Is there a way(any module or either) to restrict moderators to administer only few roles and not admins' role? Is there any other way to do this?

I am looking something similar to this sandbox project, but I want different set of permissions.
This module might be what your looking for. http://drupal.org/project/administerusersbyrole

With it you will get permissions for any role to change any other role. Here is a screen shot of it in action on the permissions page.