Your Payment Method Was Declined.

Dear sir/madam, i am from Pakistan. i have iPhone 7 OS ver. 12.3.1. i want to buy apps/games from apple app store, when i try to pay from my credit or debit card , "YOUR PAYMENT METHOD WAS DECLINED" message popup. i changed my card & try to buy but same massage received..i am unable to buy any thing from app store.. while i successfully buy from other online store from same credit or debit cards. i only facing an issue when i try to buy from app store. i request please help me out. thnx