When content is displayed through iframe, krpano will only get the domain name from the src attribute of the iframe, which will be your domain.
You should disable iframing of your site content through 'X-Frame-Options' header of apache web server. You should be able to white list the domains that you want allow iframes on through that header.
Or, you can try using javascript to verify domain name before allowing your tour to be displayed in iframe. Something like this:
if (self === top) {
show_tour();
}
else {
if (top.location.hostName === 'your-client-domain.com') {
show_tour();
}
else {
do_not_show_tour();
}
}