$re = '/<span class="icon(.*?)><\/span>/m';
$str = '<p style="text-align: center;"><span style="font-size: 1em;">Text 1 <span style="font-weight: bold;">TEXT 2</span><span style="color: #e67e23; font-size: 1.2em;"><span class="icon x-small icon-play"></span> </span><span style="color: #e03e2d;">Text 3</span> <span style="color: #a68965;">Text 4 </span></span><span style="font-size: 0.7em; color: #000000;">Text 5</span></p>';
preg_match_all($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