You say "the file" has the following commands. Is it a script ? If so, you need to make sure you have chmodded it 755, and it probably won't hurt to have a shebang line at the top. Then you call the script from the crontab.
/sbin/iptables-save > /home/user1/iptables_bkp.txt
/sbin/iptables-restore > /home/user1/original_iptables.txt
/sbin/service iptables save
/sbin/service iptables restart
save as my_script.sh
chmod 755 my_script.sh
chown root:root my_script.sh