Do the cloudflare have any restriction or sanction for Iranian users ? Can we use the pro plan ?
AFAIK Cloudflare does not impose any such restrictions, however it would seem Iranian ISPs (maybe not all) restrict certain Cloudflare IP addresses when it comes to TLS communication. There are plenty of threads here on the forum where people addressed such issues.
So you should be able to order a paid plan, but there is a good chance your site might not be fully reachable as long as you try to proxy TLS over Cloudflare’s proxies.