The mass arrests were linked to an unprecedented, independently-organized, and non-binding vote last July to select opposition candidates for a since-postponed legislative election.
The sanctions freeze any US assets of the officials, prohibit them from carrying out business in the country and generally bar Americans from doing business with them.
The Yuen Long attack, and the police's apparent failure to prevent it, exacerbated tensions during protests last year, plunging the global financial hub into crisis.
The office will oversee the Hong Kong government's enforcement of Beijing's sweeping national security legislation.
Fueling the scramble, Britain, Australia, Canada, the United States and Taiwan have all proposed measures to help accommodate Hong Kongers.
"I’m scared of going to jail but for justice I have to come out today, I have to stand up," said one 35-year-old man who gave his name as Seth.
The new operation likewise focused heavily on protests in Hong Kong, but also promoted messages about the coronavirus pandemic, exiled Chinese billionaire Guo Wengui and Taiwan, the researchers said.
It was the first time there had been unrest during the annual Tiananmen vigil in Hong Kong, which police had prohibited this year citing the coronavirus crisis.
Hong Kong democracy activist Joshua Wong said the security law will be "the death of freedom in Hong Kong."
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