When children begin to whine, the most important thing to do is not to give in. If you do, it will teach your child that whining is a good way to get what he wants, and he will do it again, and again. Instead, let him know that you expect him to speak to you without whining.
Praise your child when she doesn't whine. And if she keeps whining, stay calm and ignore it until she speaks properly. If you think she is really overwhelmed by a situation, though, she may need a hug or a back rub to break the cycle.
Here are a number of suggestions for preventing whining:
Watch for situations where your child may get bored, and prepare for them. For example, have a bag of toys for your child to play with while you're on the phone.
Teach your child the difference between whining and asking properly.
Try to pay attention to your child when she talks to you in a normal voice. If you ignore her when she is asking for something nicely, she may start to feel that the only way to get your attention is to whine.