I contacted the visa agency just now and I was told that even if you get the
visa from Chinese embassy in Iran, it would be so hard to extend your visa
in China. Generally, they don't accept the extension material for Business
Visa with the nationality of Iran. Therefore, I'm afraid we are unable to
have you this time. We really appreciate your architectural capability, and
we hope you can join us when the policy changes in the near future.
Terribly sorry about that.
All my best,