The fight occurred at about 4 p.m. Saturday in the first block of Jefferson Street.
The two men got into a fight and the suspect punched the other man, causing him to fall, according to police.
The 43-year-old victim was taken to San Francisco General Hospital to be treated for his injuries, police said.
Police responded to the scene and arrested the suspect, a 31-year-old man whose name has not yet been released.
