In a way, you could say that Reverend Parris is the main cause of the witch trials that occur in the play.
It is Parris who finds the girls in the woods. You can't really blame him for that. But he must have raised his daughter in a pretty strange way if her reaction to being caught doing something wrong is to faint and stay unconscious (or pretend to be) for a long time. So you can blame him for that.
So once she's like that, what does he do? He starts to try to protect his own reputation and he starts talking about how the devil must be out there among the people.
So you can blame Parris for setting a tone for his daughter and the people that will make them hysterical. And you can blame him for trying to point the finger at other people so as to make sure no one blames him for what is going on.
Reverend Parris discovered his niece, daughter, and servant dancing in the woods, along with other girls from the village. He understood that the spectacle would raise suspicion of witchcraft among the people of Salem, and he would be implicated. He tried to downplay the event but eventually took advantage of the situation to protect his position and punish a faction in the community that he suspected actively opposed him.
Parris seemed glad when the girls started mentioning people they saw with the devil because it distanced his family from the situation. The fact that the girls were found dancing and conjured the dead was quickly forgotten, and the focus was redirected at those who were mentioned by the girls. Hale tried to stop the trials when he discovered that the situation was marred with falsehood and pretense, but Parris would have none of it because the trials were in his favor. Thus, it is safe to blame Parris for the trials due to the role he played in instigating them and his active participation in the sham.