"This is a serious violation of the international law and main norms of the international relations, this is a gross interference in China's domestic affairs ... China resolutely opposes it", Zhao said at a daily briefing.
Beijing will implement necessary measures to retaliate, the spokesman added.
Beijing Expresses Protest Over New US Sanctions Related to Hong Kong
© AP Photo / Vincent Yu
The US Department of State announced earlier in the day that the country would impose sanctions against financial organisations conducting transactions with 24 more Chinese and Hong Kong officials whose actions "reduced Hong Kong's autonomy". The statement was made just one day ahead of a high-level meeting of the US and Chinese officials in Alaska.