Parents love their children and would want to do everything to keep them safe. As a result of this, they may sometimes prevent you from doing certain things that you ordinarily want to do, if they think you might get into trouble . If your parents prevent you from visiting your friends, it is most likely that they think you are too young to go out unaccompanied or they are not sure about your safety at your friend’s place. It could also be that they have observed some behaviours in your friend that they are not comfortable with.
What you can do is to discuss your worries about this with your dad or mom. I’m sure they will let you know their own concerns.