The White House said it also was increasing restrictions on North Korea, Eritrea, Russia and Syria, which already were on the list, by constraining them from engaging in educational or cultural exchange programs with the United States.
In addition, President Donald Trump's administration instructed the US executive director of the International Monetary Fund and US executive directors at other multilateral development banks to vote against extending loans or other funds to North Korea, Russia and Iran for fiscal year 2018, which begins on Sunday.
Under a 2000 US law called the Trafficking Victims Protection Act, the United States does not provide non-humanitarian, non-trade-related foreign assistance to any country that fails to comply with minimum standards for eliminating trafficking and is not making efforts to do so.
The White House said in a notice that Iran, Venezuela, the Democratic Republic of the Congo (DRC), Equatorial Guinea, South Sudan and Sudan had been added to the list of countries subject to these restrictions for the new fiscal year.
The move came six days after Trump included Venezuela and Iran on a list of eight countries targeted for travel restrictions to the United States. The restrictions on Venezuela focused on government officials who the Trump administration blamed for the country's slide into economic disarray. The travel ban on Iranians was broader.
That travel ban list lifted previous restrictions on citizens from Sudan.