Possible to block visitors from America without blocking google?

For certain reasons i want to block visitors from America to one of my sites. I previously tried doing this by blocking the range of ip's but that seemed to also block Google which then made my site disappear from the serps.

Does anyone know how i can do this while still allowing Google to access my site and keep it indexed.

Its quite urgent and important, any advice will be appreciated

Check User-Agent, do not block visitors with User-Agent contains "google bot"

youngguy said:

Check User-Agent, do not block visitors with User-Agent contains "google bot"

Click to expand...

Can you explain more please? sorry im a bit confused lol