The United States is imposing new visa restrictions on Chinese and Hong Kong officials over guilty verdicts in the National Security Law trial of pro-democracy organizers in Hong Kong, the State Department said on Friday.

Fourteen Hong Kong pro-democracy activists were found guilty and two were acquitted on Thursday in a landmark subversion trial that critics say could deal another blow to the city's rule of law and its reputation as a global financial hub.

"The United States is deeply concerned by the guilty verdicts announced in the National Security Law trial of pro-democracy organizers in Hong Kong," State Department spokesman Matthew Miller said in a statement.

"The defendants were subjected to a politically motivated prosecution and jailed simply for peacefully participating in political activities protected under the Basic Law of Hong Kong."

As a result, the United States will impose new visa restrictions on the Chinese and Hong Kong officials responsible for implementing the security law, Miller said.

The verdicts in Hong Kong's biggest trial against the democratic opposition come more than three years after police arrested 47 democrats in dawn raids at homes across the city. 

They were charged with conspiracy to commit subversion under a national security law imposed by China.

The U.S. urges Chinese and Hong Kong authorities to stop using the "vague national security laws to curb peaceful dissent," Miller said.