Prosecutors said the injured officer sustained a laceration and severe swelling above his left eye and was transported to a hospital and received stitches. Sermon, prosecutors said, was identified by police body camera footage.
Paul and other guests had assembled last Thursday at the White House, where President Trump accepted the Republican presidential nomination.
As the festivities were ending, police were called in as White House guests were confronted by protesters. Paul was escorted to a nearby hotel as demonstrators shouted at him.
Days after the incident, Trump criticized D.C. Mayor Muriel E. Bowser (D) about how the city and police handled the confrontation between White House guests and demonstrators, saying the mayor “did a very poor job.”
On Monday, Bowser defended the use of force by police to quell the unrest in D.C. during recent nights, including overnight Thursday, and blamed the more recent clashes on “outside agitators.”
Bowser also criticized prosecutors for not filing charges against demonstrators who were arrested on charges of assault or destruction of property. But Michael Sherwin, acting U.S. attorney for the District, said the officers provided enough evidence against many of the arrestees to justify charges.
Prosecutors did not say whether Sermon was one of the demonstrators who confronted Paul. After his arrest early Friday, a D.C. Superior Court judge ordered Sermon released from custody and to return to court for his next hearing.