I need to add rel="nofollow" to the button provided by "views load more" module
I found the answer myself, and I want to share it in case someone have the same problem in the future.

Just override the theme_pager_next() function in the template.php file of your theme like this:

function YOURTHEME_pager_next($variables) {
  $text = $variables['text'];
  $element = $variables['element'];
  $interval = $variables['interval'];
  $parameters = $variables['parameters'];
  global $pager_page_array, $pager_total;
  $output = '';

  // If we are anywhere but the last page
  if ($pager_page_array[$element] &lt; ($pager_total[$element] - 1)) {
    $page_new = pager_load_array($pager_page_array[$element] + $interval, $element, $pager_page_array);
    // If the next page is the last page, mark the link as such.
    if ($page_new[$element] == ($pager_total[$element] - 1)) {
      $output = theme('pager_last', array('text' =&gt; $text, 'element' =&gt; $element, 'parameters' =&gt; $parameters,'attributes'=&gt;array('rel'=&gt;'nofollow')));
    }
    // The next page is not the last page.
    else {
      $output = theme('pager_link', array('text' =&gt; $text, 'page_new' =&gt; $page_new, 'element' =&gt; $element, 'parameters' =&gt; $parameters,'attributes'=&gt;array('rel'=&gt;'nofollow')));
    }
  }

  return $output;
}


I've just add 'attributes'=>array('rel'=>'nofollow') to theme() function :)