One of the four major branches of Syria's security forces, the Syrian Political Security Directorate, was designated for engaging in the commission of human rights abuses in Syria.
The chief and deputy chief of Iran's national police and the head of the Syrian Air Force Intelligence were also sanctioned according to an announcement by the Department of Treasury.
"Today's action builds on the Administration's efforts to pressure Assad and his regime to end the use of wanton violence and begin transitioning to a system that ensures the universal rights of the Syrian people," said the Acting Under Secretary for Terrorism and Financial Intelligence David S Cohen.
"Also today we are exposing further Iran's provision of its military and security forces to support the Syrian government's ongoing violence and repression of the Syrian people," he said.
The Syrian Political Security Directorate is subordinate to the Ministry of Interior and one of four major branches of Syria's security forces and was slapped with sanctions.
Also designated today were Ismail Ahmadi Moghadam, the chief of Iran's Law Enforcement Forces (LEF), and Ahmad-Reza Radan, the deputy chief of Iran's LEF.
The State Department spokesman, Mark Toner, said the ruling Syrian regime needs to do a lot more, including allowing peaceful protests.
"The baseline here is allowing peaceful protestors to demonstrate and not firing on innocent protestors and just to cease all violence against these demonstrators," he said.
"I don't think anybody's getting too enthusiastic about these initial steps, but just to say that these are the types of things that need to happen.
You need to have the opposition be able to meet and have space to organize itself," he said in response to a question.