First of all, someone must apologize! My second step would be to ask for help. One good way to do this would be to ask someone from the offended culture to come talk to my employees and help them understand the culture. Third, I would try to arrange some social events that would expose my employees more to the culture. Finally, I would probably provide some goods or services for free as a way of making amends.
We are living in a global market now, and it is up to us to be informed of the cultures in which we seek to do business. Countries outside of the United States, for example, in Europe, tend to be better at this because other countries and cultures are only a few hours away. In the United States, because we occupy so much of one continent and share a common culture and language, we are somewhat lazy about acquiring the knowledge necessary to transact business properly in other countries. If we want to be part of the global village, it is up to us to be informed.