Companies like Li & Fung Ltd., which designs, sources and transports consumer goods from Asia for some of the world's biggest retailers, are being pushed by their American clients to shift production out of China.

Spencer Fung, chief executive officer said: "U.S. clients are definitely very, very worried. Everyone is making razor-thin margins already and most people have a huge percentage in China. So if the biggest source increases the price by 25%, they are worried."

And although he didn't specify Walmart by name, the US retailer is the company's second largest customer, accounting for 7.6% of its revenue.