block hotspot users to ping each other

i have setup hotspot on my mikrotik and it is working but when the users is connected with username and password then they are able to ping the other users. How can i make it possible so that they cannot ping each other. But to allow 2 ips to ping each other.

I want to enable ip 192.168.8.3 and 192.168.8.6 to ping each other and share data but not any other computer in that range that connect to the hotspot. Hotspot ip is 192.168.8.1/24 an im using dhcp with ip pool