The United States on Friday slapped sanctions on another senior Iranian official over a crackdown on protests but said Tehran appeared to be following through on de-escalating military tensions.
The United States said it was blacklisting Revolutionary Guards Brigadier General Hassan Shahvarpour for crushing protests in November in the southwestern city of Mahshahr.
The city, home to many from Iran's Arab minority, was a hotbed of protests that broke out after an abrupt hike in fuel prices. Amnesty International says hundreds died across the country.
"He oversaw the massacre of 148 helpless Iranians in the Mahshahr region," Brian Hook, the US pointman on Iran, told a news conference.
He said that the United States had received 88,000 tips from Iranians about November's protests after appealing for information to break through internet restrictions.
"We are continuing to review all information we received from the Iranian people and we will continue to hold more regime officials responsible for human rights violations," he said.
The sanctions mean Shahvarpour is banned from entering the United States -- a symbolic step as President Donald Trump has stopped visas for virtually all Iranians, from inside or outside the government.
The United States earlier this month killed the powerful head of the Revolutionary Guards, Qasem Soleimani, in a drone strike in Baghdad after months of rising tension and rocket attacks on US forces in Iraq.
Despite a fiery sermon Friday by Supreme Leader Ayatollah Ali Khamenei, Hook said that Iran did not appear to be escalating the military conflict.
"They appear to be standing down for now," Hook said.
"But we have a combination of maximum economic pressure and restoring deterrence by the credible threat of military force if attacked," he said.