The US has said more than 60 of its main trading partners engage in unfair practices and that copyright theft in China remains its main concern.
In a report to Congress, the US Trade Representative said US companies were facing "significant" barriers to trade and investment around the world.
It said it would refer China to the World Trade Organization unless it did more to protect intellectual property.
It also pledged to continue its fight to curb subsidies to planemaker Airbus.
'Barriers'
The US and European Union have been locked in a long-running stand-off about allegations of state subsidies to both Airbus and US rival Boeing.
Despite a number of successes in the past year, such as Vietnam's entry into the WTO, Washington said it was encountering unfair barriers and protectionism in 63 main trading partners, including the EU.
"A significant amount of work remains to knock down trade barriers and ensure that American exporters have new economic opportunities around the globe," said Susan Schwab, the US Trade Representative.
Key priorities for the year ahead include working with Beijing to ensure tougher enforcement of copyright across a range of industries and curbing what the US says are unfair subsidies given to medium-sized Chinese firms.
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