Secretary of State Mike Pompeo said on Tuesday that the US would hit with sanctions Iranian officials who are responsible for the crackdown on protests during the past 10 days.
Mr Pompeo told of the “courageous people of Iran who refuse to stay silent about 40 years of abuse by the ruling regime".
“The United States hears you, we support you, and we will continue to stand with you,” he said.
Amnesty International estimated that at least 143 protesters have been killed by Iranian security since November 15.
Mr Pompeo said the US had received almost 20,000 messages, videos and pictures of the regime’s abuses.
The content will be used to pursue Iranian officials involved in the crackdown.
“We will continue to sanction Iranian officials who are responsible for these human rights abuses,” Mr Pompeo said.
He called Turkey's tests on Monday of its new Russian S-400 missile system “concerning”, but stopped short of imposing sanctions.
“We made it very clear to Turkish government about our desire to see them move away from putting into full operational the S-400 system,” Mr Pompeo said.
“We are hopeful. We are still talking to the Turks, still trying to figure out our way through this thing.”
He also urged Egypt to release journalists it detained last week from the news website Mada Masr.
“We call on the Egyptian government to respect freedom of the press and release journalists detained during a raid last weekend," Mr Pompeo said.
Mr Pompeo said he had no update on Lebanon and the military aid that the Trump administration had put on hold.
He will travel next month to the UK for a Nato summit and visit Morocco and Portugal.