Merely pointing a domain at your site isn't enough to make things work. What's happening here:
- You have WordPress configured on the
- Traffic from the
.ir domain is pointing at the same server
- WordPress doesn't realize they're the same thing and instead assumes you're trying to set up a new blog on a multisite installation
You'll need to tell the server how to handle the
.ir requests. If you want these domains to serve the same site, you'll likely need to set one to redirect to the other. Meaning anyone who visits the
.com is redirected to the
.ir (or vice-versa, depending on your preference).
WordPress Multi-site will otherwise treat these as separate sites within your installation.
If you need both domains to be treated as separate sites, but still serve the same content, take a look at a domain "alias" plugin like Mercator.