My juniors at work are rebellious

Dear Counsellor,

I was recently promoted at work so very many people report to me now. Before I was promoted, I was a cool person, I still am. I joked around a lot. And I think it is for this reason that people do not take me seriously. I can handle a few clashes from time to time but now this is downright hostility and ridicule. Some even reach the point of shouting at me, telling me to get the work done myself if I want it done so badly. I do not want to take this case to Human Resource department as I will come off as a snitch and perhaps even a ‘cry baby’. But I need ways to put them in their place, for them to understand that work is work. They come in late and when I ask them about it, they simply say they had issues to take care of, and walk off. It’s driving me crazy. How can I handle this in a mature way without involving top management? Of course if the worst gets to the worst, I might just have to resort to that.