PHP禁用iFrame外部链接

I have a iFrame on my website. The problem is, that if you press the iFrame, sometimes it loads a advertising page instead of the URL it should show.

Is there a possibility to disable all external links (so that you can just go to the root URL's - http://mywebsite/...) and allow just some external links (those the iFrame should link to)

Or if the blocking doesn't work is there a possibility to show the advertisement in a new browser site?

Since the iframe loads the website as it is, no, there is no way to block specific websites that are loaded FROM the website itself. You can't control what the website you're loading loads itself.