Do I need to pay GST on incoming international transaction?

For domestic you dont pay differential GST. You claim ITC on purchases and pay GST on sales. Net effect is differential but the liability of GST is on the sale value.

As far as international transactions are concerned and assuming they are in the nature of exports then either you have to supply under LUT without tax or pay GST and claim refund of tax paid.

In case of further confusion engage a professional