The move against Communications Minister Reza Taghipour came after he was blamed for ordering the jamming of international satellite TV broadcasts and restricting Internet access, a State Department official said.
The United States was determined to stop the "Iranian government from creating an 'electronic curtain' to cut Iranian citizens off from the rest of the world," said State Department spokeswoman Victoria Nuland.
Four individuals and five bodies were placed under sanctions by both the State Department and the US Treasury for "censorship or other activities that prohibit, limit or penalize freedom of expression or assembly by citizens of Iran."
They were also accused of limiting "access to print or broadcast media, including by jamming international satellite broadcasts into Iran," Nuland said in a statement, denouncing the "regime's insidious actions."
Internet users in Iran were temporarily unable to access their Gmail accounts from late September to early October.
Mohammad Reza Miri, a member of the telecommunications ministry committee tasked with filtering the Internet in Iran, was quoted by the Mehr news agency as saying that the Gmail block was an "involuntary" consequence of trying to reinforce censorship of Google's YouTube video-sharing site.
"Unfortunately, we do not yet have enough technical knowhow to differentiate between these two services. We wanted to block YouTube and Gmail was also blocked, which was involuntary," he said.
"We absolutely do not want YouTube to be accessible."
Iran has censored YouTube since mid-2009, after opposition demonstrators protesting the re-election victory of President Mahmoud Ahmadinejad in polls they believed rigged started posting videos online of their gatherings.
Iran's ministry of culture and Islamic guidance was also sanctioned for closing down newspapers and detaining journalists.
Other entities targeted included the Press Supervisory Board and the Center to Investigate Organized Crime, which helped "identify Internet users who published material insulting government officials," the US Treasury said in a statement, adding some of the people were later arrested.
"Finding that balance between preventing technology that could constrain and permitting technology that would expand their access to information is kind of a difficult question," a senior State Department official told journalists.
Also included in the designations were Ali Fazli, a deputy commander of the Basij militia blamed for launching attacks on foreign websites, including foreign media organizations, and Iran police chief Esmail Ahmadi Moghaddam, who is in charge of tracking Internet activities in the country.
Iranian software companies AmnAfzar Gostar-e Sharif and PeykAsa, as well as their founder, Rasool Jalili, were also targeted for monitoring Web traffic, including moves to block access to Facebook, eBay and YouTube.
The Iranian government was engaged in a campaign to "curtail" freedoms and "prevent the free flow of information both into and out of Iran," Nuland said in her statement.
"Countless activists, journalists, lawyers, students and artists have been detained, censured, tortured or forcibly prevented from exercising their human rights," she added.
The new designations resulted from an August 2012 act that came into force on Thursday and mean Americans are banned from doing any business with the targeted Iranians, who are also barred from traveling to the United States.
Any of their assets in the United States will also be frozen.
Other newly rolled out sanctions focused on individuals designated for sponsoring terrorism, in particular the Kata'ib Hezbollah group responsible for violent attacks in Iraq.
A third tranche of the designations targeted the support network of the Iranian Revolutionary Guards Corps -- including the National Iranian Oil Company, which is already under sanctions, and two Tehran universities.