Ratings firm Moody's said on Tuesday that potential auto tariffs by the United States would be a risk to global growth, hindering economic momentum in Germany, Japan and Korea.

However, such a move would be less severe for China as Chinese vehicle exports were already subject to trade restrictions, Moody's said in a report, adding that it would also be broadly credit negative for the global auto industry.

"Auto trade restrictions would cause a broader hit to business and consumer confidence globally in an already slowing global economy," Moody's Associate Managing Director Elena Duggar wrote.