Is the percentage deducted by the local bank, which it took in exchange for withdrawing a sum in dinars before the dollar transfer arrived from an external account, considered usury (riba) forbidden by Islamic law, knowing that the customer was not aware of this condition beforehand and was the aggrieved party?

Usury is a grave sin, and a believer is required to avoid any usurious transaction. Depositing money in usurious banks constitutes cooperation in sin. Your question contains two prohibitions: The first is that paying checks in dollars and receiving their equivalent in dinars before the amount arrives is considered usury, because currency exchange must be hand-to-hand. The second is that overdraft, which is a loan from the bank, and taking a percentage on it, is usury. However, since you were unaware of the religious ruling, we hope that there is no sin upon you. Your duty now is to withdraw your money from the usurious bank and deposit it in an Islamic bank, and not to return to depositing in a usurious bank except out of necessity.