The government already doing something about this minors problem and gambling site too have implemented the method to prevent this.
So,it depends on the individual now,the parents or adult around them should educate these minors to not involve themselves to any kind of gambling activities online or offline.
Without the cooperation of parents or guardians, the problems of gambling among minors won't end. It's not that these guardians should keep those minors away from gambling but just give them a serious talk about gambling in general. Parents can do it while having lunch or dinner while watching TV with them etc.
The government is just there to help and assist everyone regarding that problem but the solution should come from the home.
That's where the proper discussion should be.