The U.S. Park Police were notified of the paint -- a spatter of green across Lincoln's left leg, the front of his chair and in his lap -- early Friday morning.
Police said they would close the memorial to visitors while an investigation takes place, including a review of surveillance video, and the paint is removed. U.S. Park Police Capt. Steven Booker gave no timeframe on how long the cleanup would take or when the memorial would be reopened.
Booker noted that, while there were no symbols or letters visible in the paint, the spill "appears intentional based off the splatter."
Lincoln joins the Washington Monument, the Martin Luther King Jr. Memorial and the White House tour as highlights of D.C. tourism with limited access.
The Washington Monument has been closed since the August 23, 2011 earthquake, when the elevator was damaged and stones and mortar loosened.
Scaffolding was put up Monday around the main statue of the Martin Luther King Jr. Memorial, which was finished in the fall of 2011, to remove a paraphrased quote that critics said skewed King's original meaning.
The stone on the side of the statue read "I was a drum major for justice, peace and righteousness," but King actually said: "If you want to say I was drum major, say that I was a drum major for justice, say that I was a drum major for peace. I was a drum major for righteousness. And all of the other shallow things will not matter."
Work on the King memorial was initially supposed to begin in February and take two months.
Public tours of the White House were canceled March 9 to reflect staffing reductions as a result of cuts from the sequester.