No, you cannot travel internationally without US passport after becoming a citizen.
Reschedule your travel plans if you can. Really consider it. I can't imagine becoming a citizen can be a lower priority than travel, be it business or leasure.
I can never recommend rescheduling. Sometimes USCIS will forget about you and you may end up trying to reach them to get an update for many months.
If you're ready to put some effort and test your luck, you can actually attend the ceremony, get naturalized and do your best arranging an urgent passport appointment. If you have 3 weeks or so between naturalization and and trip, you may be able to pull this off.
Good luck!