The bank said net mortgage lending dropped by €69m in July, which was the fourth monthly fall in a row.
This means that the amount repaid on existing mortgages was greater than the amount of new mortgage lending.
The annual rate of growth in mortgage lending fell to 1.2% from 1.9% in June.
Total lending in the economy fell by €3.7bn in July - the fifth monthly fall in a row - mainly due to the write-downs of loans and increased provisions for bad debts.
The Central Bank also said that the amount owed by households fell €404m in July, with repayments on credit cards again exceeding new spending.
