What can be done if the mother is taking the children away during father's visitation time?

My children's mother was just granted the right by the courts to move to California from New York. Part of the settlement was that I the father am to have the full month of July with my children. Their mother has planned a 7-day cruise to Hawaii, Belize, Honduras, and Mexico, with my children during the first week of July (my time) without my consent. Is there anything that I can do to prevent this and what can I do if she does take them? Thank you for your time and your help.