"tourism company" is not a very meaningful definition for a native speaker. There are a few types of companies which operate in the tourism sector, such as travel agents, package tour operators, holiday accommodation providers. The terms may be different in the USA too. Certainly, the British word "holiday" is "vacation" in the USA. If you tell us specifically what kind of work your company did, hopefully we can help you better.

You can put it this way, "I worked in customer service for a tourism company." Hope it helped :)