Iptables

I'd like to block access to Internet from a local machine (192.168.168.3) but I need some IP's to be still available.
Is there any way to include txt list of these IP's for iptables ?

And am I correct with this ?
iptables -t nat -A OUTPUT -i eth1 -d 192.168.168.3 -s ! -j DROP

Thanks in advance !