$re = '/\<div.*\>((.*|\s|\r|\n)*)\<\/div\>/m';
$str = '<div class="1" >quero pegar
AQUI DENTRO PODE TER
quebra de linha...
paragrafo...
espaços
várias outras tags html...
qualquer coisa...
<p> Teste </p>
<p><span> Teste <span> </p>
</div>';
$subst = "$1";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
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