Jovetic opened the scoring in the 11th minute, starting a run of four straight goals for Manchester City in its Pool B opener. His right-footed shot beat goalkeeper Ian Lawlor to the near post.
Scott Sinclair added a goal three minutes later and the rout was on. Jesus Navas made it 3-0 in the 23rd and Kelechi Iheanacho tacked on the fourth three minutes after that.
Milan finally scored in the 42nd through Sulley Muntari, but Jovetic used his left foot to restore the four-goal lead in the 58th.
Manchester City continues Pool B play July 30 against Liverpool at Yankee Stadium. AC Milan faces Liverpool Aug. 2 in Charlotte, North Carolina.