The new rules, implemented to preserve safety and modesty, according to a spokesman for the Diocese of Harrisburg, also ban girls from joining football and rugby teams.
Reuters saw the letter Bishop Ronald W Gainer sent to parents.
It said: "The diocese therefore believes that it is incompatible with its religious mission and with its efforts to teach Gospel values to condone competitions between young men and women in sports that involve substantial and potentially immodest physical contact."
The policy only applies to schools and will not affect university students.
It means that a male would have to forfeit a wrestling match with a girl or urge the opposite team to choose a boy instead.
It is thought that up to 30 girls are members of wrestling clubs in Pennsylvania.