The department said in a statement that employees working at the US embassy in Baghdad and the US Consulate in Erbil were required to leave Iraq, and "normal visa service will be temporarily suspended in both posts . "
It further added that employees of American Citizens Services working in the embassy in Baghdad "will continue to provide consular services to United States citizens in Basrah."
The department said that the sudden changes were because "the ability of the United States government to provide regular emergency services to US citizens in Iraq is extremely limited" and the result is the goal of "terrorism, kidnapping, and armed conflict" among Americans in the country is a huge threat.
Secretary of State Mike Pompeo made an unspoken visit to Iraq last week amid rising tensions in Iran.
While there, Pompeo said he talked with Iraqi officials "about the importance of Iraq ensuring that it is enough to protect Americans in their country."
US officials told CNN that the US has "certain and credible" The proposed Iranian forces and proxies are planning to target US forces in locations including Iraq. This intelligence led the Pentagon to recommend a group of strike groups transferred to the region.
The State Department also said Wednesday that Americans "should not travel to Iraq in Syria to take part in armed conflict" because they can deal with similar threats to Syria and deal with "legal risks" from both US and Syria.
Urban statement also said against comments made Tuesday by the deputy commander of the US-led military coalition against ISIS, UK Major Gen. Chris Ghika, who said "no further threat from Iranian back forces in Iraq and Syria."
Ryan Browne and Jamie Crawford of CNN contributed this report.