$re = '/(?(?=\/.?)|({if \$var3}).*?)*(?={\/if})/msi';
$str = '{if $var1}
{if $var2}
{if $var3}
text *(&@$@!/\\#<?>~`.,+-_
{/if}
{/if}
{if $var4}
any symbols
{elseif $var5}
text
{else}
{if $var6}{/if}
{/if}
{if $var7}{/if}
{else}
text and symbols *(&@$$@!
{/if}';
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