A Boston police officer responding to a domestic assault Friday evening was attacked by a suspect in the South End, police said. Spokeswoman Nicole Grant said two officers responded to reports of a man assaulting his girlfriend on Harcourt Street shortly before 6:30 p.m. when the suspect, Michael Sheridan, 32, allegedly lunged at the officers and put one of them in a choke hold. The officer was taken to Tufts Medical Center with a neck injury, Grant said, but was released later Friday. Sheridan, of South Boston, was also taken to Boston Medical Center for an evaluation, police said. Sheridan was arrested, although it was not immediately clear what charges he is facing.Nicholas Jacques can be reached at email@example.com.