bbPress.org

I also need something like that.
Is there any plugin or code?

You can use bbp_get_reply_content filter, but this can be a disaster when you take off all the links that other plugins or the theme could have in the reply content. A good example is the mentions being added by BuddyPress, but after using this, they turn into the restriction notice..

add_filter('bbp_get_reply_content', 'restricted_links', 20, 2);

function restricted_links($content, $post_id) {
  if ( is_user_logged_in() )
    return $content;

  return preg_replace_callback( '/<a(.*?)href(.*?)>(.*?)<\/a>/si', function($m){
    return sprintf(
      '<span class="protected-link" style="background:#f3f3f3;padding: 2px 5px;display:inline-block;border-radius:3px">[Restricted Link] Please <a href="%s">register</a> to view this link</span>',
      home_url('/wp-login.php?action=register')
    );
  }, $content );
}

You may pass-in the link text after the notice or something, it is all up to you so play around with the code or ping me if you needed help.