$re = '/(<blockquote\s*[^>]*>(.*)<a\s*[^>]*(?:href=["\']([^\'\"]+))\s*[^>]*>(?:[\S\s]*?)<\/a>(.*)<\/blockquote>)/i';
$str = '<blockquote class="bs-callout bs-callout-info comment"><div class="author"><a class="comm_link" href="#comment_1"> Лев Сорокин says:</a></div> ÑброÑить пароль <a href="#user_4">Тимур Данилов</a> в <a href="#supplier_1">ООО Ромашка</a></blockquote>
СброÑил
<blockquote class="bs-callout bs-callout-info comment"><div class="author"><a class="comm_link" href="#comment_2"> Ðнджела шубина says:</a></div>Ðичего не делать</blockquote><br>
Ок =)
<blockquote class="bs-callout bs-callout-info comment"><div class="author"><a class="comm_link" href="#comment_4"> Людмила ÐекраÑова says:</a></div>aaaaa<blockquote class="bs-callout bs-callout-info comment"><div class="author"><a class="comm_link" href="#comment_5">comment_1</a></div> fffffff </blockquote>qqqq<div></div></blockquote>';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php