"The designated individuals and entities have provided support or services to the government of Syria, or are owned or controlled by or are acting for or on behalf of designated individuals or entities," said the US Treasury Department in a statement.
Among those being sanctioned were relatives of Rami Makhluf, a powerful businessman in Syria and a cousin of Syrian President Bashar al-Assad.
The US Treasury Department also sanctioned Muhammed Bin-Muhammed Faris Quwaydir, contracts director of Scientific Studies and Research Center (SSRC), for acting for or on behalf of SSRC, the Syrian government agency responsible for developing and producing non-conventional weapons and the means to deliver them.
Last month, the United States slapped sanctions on 271 employees of the SSRC in response to the Syrian government's alleged use of chemical weapons.
The sanctions are part of Washington's response to what it believed was the April 4 sarin attack on innocent civilians in Khan Sheikhoun in east Syria by the Syrian government.
Two days after the alleged chemical attack, the United States launched 59 Tomahawk missiles at a Syrian airbase to neutralize its chemical weapon arsenal.