That’s a view of the front entrance to their embassy. No flag is visible, for what it’s worth. I’m going to look for photos of the Scandinavian embassies.
It looks like the Swedish embassy displays its flag (scroll through photos).
https://www.google.com/search?q=sweden+embassy+in+tehran&oq=sweden+emb&aqs=chrome.2.69i57j0l3.11761j0j4&client=ms-android-verizon&sourceid=chrome-mobile&ie=UTF-8#fpstate=lie&xxri=28