Frustrated U.S. businesses can no longer be counted on as a "positive anchor" in U.S.-China relations, a top U.S. business lobby said, arguing any deal to end trade tensions must address structural problems in China's economic system.

"Crucially, the mood has shifted," the American Chamber of Commerce in China said in a statement accompanying its annual report on China's business climate.

"The U.S. business community in China, so long an advocate of good bilateral relations, can no longer be relied upon to be a positive anchor. U.S. companies continue to face an uncertain operating environment in China amid decreasing optimism about their investment outlook," it said.