City officials “haven’t learned their lesson” when it comes to knee-jerk judgments of police shootings, said an ex-cop who was vilified after killing a teen on a rooftop in Brooklyn.

Officer Richard Neri, was about to enter a rooftop stairwell on Jan. 24, 2004, when Timothy Stansbury opened the door and the cop fired.

Then-cop Commissioner Ray Kelly said “there appears to be no justification for the shooting.”

But a grand jury declined to indict Neri. “It’s a shame that the police commissioner and the mayor haven’t learned their lesson yet,” said the now-retired Neri.