The official did not say when that request was made, and what countries were approached, but noted that the US did not ask Russia and China for cooperation on the matter.
The unnamed official added that US authorities took into consideration the potential effect on ordinary workers from the northern state, stressing that there was no intention to completely eliminate North Korean labor.
The official noted that although analysts have asserted that the bulk of foreign earnings goes to the North Korean government, rather than their families, the workers are likely better off abroad than at home.
US State Department spokeswoman for the State Department's Bureau of East Asian and Pacific Affairs, Gabrielle Price, told Reuters that an executive order signed by Obama on March 16 provided tools to allow Washington to target North Korean labor working abroad.
"[The executive order] includes the authority to target North Korea's exportation of labor in order to provide Treasury the flexibility to impose sanctions and ratchet up pressure as needed. At this time, we are closely studying the issue," she said.
One day prior to the revelations, the United States for the first time imposed sanctions on North Korean leader Kim Jong-un, accusing him of being directly responsible for a long list of human rights atrocities in his country, including extrajudicial killings, forced labor, and torture.