The human rights abuses which take place in China should be of concern to all of the other governments on the globe, but they should be of particular concern for the US. The vast amount of money which China receives from the US through goods made in China and sold in the US puts a great deal of money into China's government coffers. The fact that remains that money is being used to support a government which continues to deny it's citizens the human right which the US has been a defender of since it's inception. The best way to convince the Chinese government that the US is still serious about defending those right is to directly effect the amount of money the Chinese government receives. Trade barrier would effect the GNP of China and truly is the best, if not only way to lead to an end to human rights abuses happening in that country.
At this point in history, China has a lot of manufacturing and trade power, and is a major player in the global marketplace. If the US put trade sanctions against China they would likely just trade with other countries, putting the US in a worse economic position and not hurting China much at all. That means those sanctions would be ineffective at changing human rights violations in China.