It seems from what you report that you are not able to establish a rapport with children in your class. Teaching children is definitely different from teaching adults. Children have a short attention span and it is difficult to make them concentrate in studies. They are likely to be naughty and playful.
My advise to you would be that you could devote one or two classes to non academic topics like sports, watching TV, cartoons, etc. In these classes you can talk about their school experience and share some of your experiences as a child with them. This will not only help you know them better but will also help you establish a rapport with them which in turn will bring you closer to your students and make your classes interesting for them. You can involve the more naughty and aggressive children in classroom readings and discussions. Once a week you can also take the students feedback about the topics covered during that week. If you have a counsellor in your school you can also take his/her help.