s_ha_dum is correct, you don't need to enqueue it yourself.
That being said, the reason your script is not working is because your dependancy variable is not an array. Your code should read:
wp_register_script('jquery_masonry', includes_url(). '/js/jquery/jquery.masonry.min.js', array( 'jquery' ) );
Way down deep in the WP_Dependancies class, if the value passes is not an array, it sets it to be a blank array, therefore making it have no dependancies. (see wp_includes/class.wp_dependancies.php line 251 as of WP 3.6, if interested)
So what I assume is happening, is it's loading in the Masonry script BEFORE jQuery is loaded in, therefore causing it to do nothing.
That being said, use s_ha_dum's response, as it's already registered in WordPress, and waiting to be en-queued.