The president was playing defense when Decerega, director of programs for the Congressional Hispanic Caucus Institute, hit him in the face with an elbow. The cut took 12 stitches to close.
"I learned today the president is both a tough competitor and a good sport," Decerega said in a statement issued by the White House. "I enjoyed playing basketball with him this morning. I'm sure he'll be back out on the court again soon."
The injury occurred during the fifth of five games of 5-on-5 the president played at Fort McNair with a group that also included his personal assistant, Reggie Love, Education Secretary Arne Duncan and Obama's nephew, Avery Robinson.
Decerega "turned into POTUS [president of the United States], who was playing defense, to take a shot when the elbow hit the president in the mouth," the official White House statement said.
Press secretary Robert Gibbs said the stitches were administered by the White House medical unit. A doctor used a local anesthetic while sewing up the president's lip.