So it means to have an account in a Pakistani bank first I will have to go to some branch there and then make an account and deposit some money and then use their online service from anywhere around the world ?
I think for pakremit etc you can just do it online via your credit card; you don't need to have a bank account. But you would need to register your details and make an online account (like you would if you did Western Union online) and they will verify your details (you need to enter your social security number and such).
Hence.. you can't register to use if your a non US citizen.