Dear Rushi,
Appreciate on you response.
The reason i'm nating the src is due to the routing issue from the server side. After create the VPN, Site B can ping to Site A firewall IP trust zone (10.20.5.27) but can't reached to the server IP (10.20.5.7)
After do the NATing, Site B can reached the server but the problem is it can only see 10.20.5.27.
I've run the config as per advice by you but unfortunately site B can't reached site A. I'm applying the policy from untrust (any) to trust (MIP) but still failed to pass through.
Regards.