Yes, the only fireworks for that evening will be with Mickey's Very Merry Christmas Party. Which if you do decide to attend, it will be a lot of fun with a special parade, snow on Main Street, and smaller waits on many of the rides.
However, if you really only want to see the fireworks, I might suggest going over to the Polynesian resort and watching them from the beach. While the view is different, I think it is just as magical watching the fireworks reflecting off the Seven Seas Lagoon. There is also a charming little parade on the water that runs nightly and comes by the Polynesian at 9 p.m.
Could I also suggest for approximately the same (or maybe even less) amount of money as the Christmas party, that you dine at the California Grill on top of the Contemporary Resort. It has incredible views of the Magic Kingdom and the fireworks. Even if you eat early in the evening, as long as you have your receipt, you are welcome to come back up to watch the fireworks from their viewing balcony.