Redirect to Page URL for non-members

You can use use wp_redirect for that. Here is a simple code, it redirects non-users to website homepage. You can redirect them to a error page or on signup page.

<?php
  if( mgm_user_is( array('level1', 'level2' ) ) ) {
    wp_redirect( home_url() );
    exit;
  } else {
    // show content
  }
?>