A month earlier, industrial sales increased by 2% compared with May.
Sales in the mining industry fell 5.2% on the month in July, while manufacturing sales were down 4.1%, the data showed.
By sector, sales in the consumer goods industry decreased 6.2% in July from a month earlier, while sales in the capital and intermediate goods industries declined 5.3% and 3.5%, respectively.
Sales in the durable goods industries were down 2.3% on the month, but energy sales inched up 0.3%, the data showed.
On an annual basis, industrial sales rose 13.5% in July, boosted by higher sales in all sectors. Mining sales were up 15% on the year in July, while sales in the manufacturing sector grew by 13.4%.
In January to July, Romanian industrial sales advanced 17.7% from the year-earlier period, again fueled by increased activity in all sectors.