Whether it is bullying or not, it is certainly an assault on your child. I have watched teachers just standby and do nothing, maybe you just remind them that your child comes to school to learn and socialise not be assaulted, if they are not prepared to take action then you will call the police and report it as an assault. Should do the trick! Hopefully, they are on the case now and that will be the end of it.
I'm sorry you're going through this, preeyabh. We are going through it as well, unfortunately it's @ home. I think you were right to address it and nip it at the bud... our daughter's behavior was actually starting to change, becoming introverted, not wanting to play anymore, being irritable and frustrated easily... It's hard and can be "awkward" but its our responsibility as parents to do our best and ensure our children's happiness...