Police spokeswoman Norma Eisenman says Alexander hit the biker Tuesday along Wilshire Boulevard in the Mid-City area.
Eisenman says Alexander stopped and waited for police and wasn’t cited.
She says the boy suffered minor injuries and was in stable condition when he was taken to a hospital for examination.
Alexander played neurotic friend George Costanza on ‘Seinfeld.’
A call seeking comment from his publicist Ron Hoffman wasn’t immediately returned.
Watch Jason Alexander on ‘The Marriage Ref:’