"It is still unclear what Trump's policies will be. We can't suddenly make production changes and that is a problem not just for us but for all automakers in the U.S.," Takahiro Hachigo said at a briefing in Tokyo on Monday.

Doing away with the NAFTA, which Trump has described as a jobs killer while attacking the outsourcing of American auto jobs to Mexico, could result in tariffs on cars built in Mexico that Honda and other makers sell in the United States.

Honda has two auto plants in Mexico, one in Celaya and the other in Guadalajara that together build around 260,000 cars and 100,000 motorbikes a year. U.S. vehicle manufacturers and many of their suppliers have based billions of dollars of investment on relatively open trade with Mexico, China and other countries.

In April, Ford Motor announced plans to invest $1.6 billion to expand production of small cars in Mexico.