Blocking wp-login on wordpress ..

If you do actually have a HTTP profile assigned, try this (I've just tidied up the test expression);

when HTTP_REQUEST {
  if { ! [IP::addr [IP::client_addr] equals 10.0.0.0/24) } { 
    log local0. "Client IP: [IP::client_addr]"
    switch -glob [string tolower [HTTP::uri]] { 
      "/admin" { log local0. "ADMIN" drop log local0. "Dropped admin [IP::client_addr]" } 
      "/wp-login" { log local0. "LOGIN" drop log local0. "Dropped login [IP::client_addr]" } 
      default { return } 
    }
  }
}

If you don't have a HTTP profile assigned, change the event to 'when CLIENT_ACCEPTED'.