I walked by a group of 9 people smoking and i am pregnant, will that harm my baby?

Very unlikely: Cigarette smoke contains many toxins and you probably breathed in a bit of second-hand smoke, but your body has mechanisms to detoxify these and the amount of toxins that reached your baby should be negligible. The effects of toxins is related to the dose, and the dose you and your baby received was so small that you don't need to worry. But pregnant women who smoke undoubtedly harm their babies.