$re = '~https?://(?![^" <>]*(?:jpg|png|gif))[^" <>]+~';
$str = 'http://www.ex1.ir/new-img/im.png
http://www.ex2.ir/d1/d2
http://www.ex3.ir/1.gif
';
preg_match($re, $str, $matches, PREG_OFFSET_CAPTURE, 0);
// Print the entire match result
var_dump($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