US officials have expressed concern that an international court ruling expected in the coming weeks on a case brought by the Philippines against China over its East Sea claims could prompt Beijing to declare an air defense identification zone, or ADIZ, in the region, as it did in the East Sea in 2013.
Work told an event hosted by the Washington Post that the United States would not recognize such an exclusion zone in the East Sea.
China claims most of the East Sea, through which more than US$5 trillion in global trade passes every year.
"We don't believe they have a basis in international law, and we've said over and over (that) we will fly, sail and go wherever international law allows," Work said.
"We have spoken quite plainly to our Chinese counterparts and said that we think an ADIZ would be destabilizing. We would prefer that all of the claims in the East Sea be handled through mediation and not force or coercion," he said.
Work spoke as Chinese President Xi Jinping prepared to visit Washington for a nuclear security summit this week.
The United States has accused China of raising tensions in the East Sea by its apparent deployment of surface-to-air missiles on a disputed island, a move China has neither confirmed nor denied.
China, for its part, has repeatedly accused the United States of militarizing the East Sea through its freedom of navigation patrols in the region and the expansion of military alliances with countries such as the Philippines.
In February, Chinese Foreign Minister Wang Yi said his country's East Sea military deployments were no different from US deployments on Hawaii.
Tensions between China and its neighbors Vietnam, Malaysia, Brunei, the Philippines and Taiwan over sovereignty in the East Sea have risen after Beijing embarked on significant reclamations on disputed islands and reefs in the area.