If you'd like to apply a rule only at certain URL paths, add this php condition:

<?php $url = drupal_get_path_alias($_GET['q']); $needle = array( 'search_pages', // 'another-url', ); foreach ($needle as $url_needle){ if (strstr($url, $url_needle)){ return TRUE; } } return FALSE; ?>

UPDATE

Looks like this module may also be helpful:
Path Rules