It could be very difficult using regex in Kate, if you have php files that have still an html (and not php) as content structure.
In this case you can try to use, al filter, not *.php, but *.*.
Moreover it could be necessary to use this regex code for multiline tags :
<style type="text/css">((.|\n)*?)</style>or
<script type="text/javascript">((.|\n)*?)</script>and so on.