Could running be helpful to reduce stomach fat?

Yes: As part of a well-rounded (no pun intended) fitness program. Running alone will help boost metabolism and burn extra calories, and the loss of fat will be evident on your abdomen, as long as you also take care to not intake excess calories at the same time. I would recommend supplementing running with toning/core work (planks, crunches, google "abs exercises") and a healthy diet.