Average diesel prices in Ireland fell to €1.73 per litre in July, a decline of 15 cents from the previous month's average of €1.88.
Petrol prices also retreated, according to the latest monthly survey by AA Ireland.
The drop marks a continued normalization of fuel costs as global crude oil benchmarks retreat to levels seen before the outbreak of the Iran war in February.
The price reductions in Ireland mirror trends emerging in other markets.
In the United Arab Emirates, petrol prices are scheduled to fall in July, marking the first reduction in five months.
Similarly, fuel retailers in the Philippines implemented significant price reductions in late June, with gasoline and diesel costs set to fall by as much as P11.82 per liter.