Django - URL with www is not safe

I have website as bukimlan.com. We set default site as shown https://bukimlan.com. There is no problem with this url. We have SSL and secure.

But if user comes with https://www.bukimlan.com URL, there is a not safe error in address line. And in mobile, google says your connection is not private with www url.

Google indexed some pages with www, so we need to solve this problem.

Thanks for your replies.