How use iframe to view a webpage on epub3?

I would embed a webpage on and ePub3 FL that should be read on iPad (but not only ;-) ); with <iframe> this work if the html file is in local but doesn't work if it is a remote-resource (i thinks due a security motivations).

I know that this is possible with a widget of iBook Author but I want an ebook ePub3 compliant (not only for ibooks).

Thanks in advance