are iframes counting as external link?

I have a page in my website which has an iframe from other domain with similar content. My website is better positioned than this website which I have embed with an iframe, and this specific html page is now over me in the google organic search (he's now #1 and I #2)!
How it would be possible? Are iframes counting as external link? If yes, how can I stop giving him some help in google organic search? is any nofollow equivalent for iframes?

Thanks