Samuel Parris' attitude toward children is told to the audience in narration in the very beginning:
He was a widower with no interest in children, or talent with them. He regarded them as young adults, and until this strange crisis he, like the rest of Salem, never conceived that the children were anything but thankful for being permitted to walk straight, eyes slightly lowered, arms at the sides, and mouths shut until bidden to speak.
This description is rather revealing about his attitude. Part of his apathetic attitude toward children probably comes from the fact that he is a widower and without the role of a nurturing woman in the house, he resorts to what is often understood by men: action, not feeling.
He could have cared less about children and obviously wasn't very good with them. As the Puritan environment around him suggests, children were not meant for play, but for subservient behavior at the beckon call of the adults around them.
As the action and dialogue of the play finally begins, we learn that this attitude is true to Parris' nature. He is forceful with Abby and certainly judgmental. He also cares less for Betty's condition than he does his own reputation.
Miller uses both narration and the action of the play to display this poor attitude of Parris toward children.