Geo-fencing for block and allow one country

It is not AFM but one work around is to make an Irule that would drop all outside connections. Something like:

when HTTP_REQUEST {

   if {  [whereis [IP::client_addr] country] != "US" } {

   drop

   }

}

This would drop all not united states based IPs. 

i am facing problem how to block all and all only one country  

Please follow the steps outlined in the article below.
https://clouddocs.f5.com/training/community/firewall/html/class1/module1/lab4.html#create-the-geo-restrict-firewall-rule-list-and-firewall-policy

i have not found Not in united stated 

Hello Khan, 

Please follow below steps to configure geo-fencing in F5 AFM to allow access only from the USA and block all other countries:

1. Log in to the F5 Configuration Utility.
2. Navigate to Security > Network Firewall > Policy List.
3. Create a New Firewall Policy.
4. Define Rules for the Policy:
   • Create an Accept rule for Source: Geolocation and select United States.
   • Create a Reject/Drop rule for Source: Geolocation and select Not in United States.
5. Save and Apply the Policy to the relevant virtual servers.