Some of the shipments were loaded in July and arrived in August, according to data obtained by Reuters from trade sources.
The August 2018 imports were still 56 percent higher than the amount for the same month last year, the data showed, as state refiners were attracted by discounts offered by Iran this year.
In April-August, the first five months of the 2018-2019 fiscal year, India's oil imports from Iran rose 43 percent to 646,200 bpd compared to the same period a year earlier, the data showed.
State-run Indian Oil Corp., the country's top refiner, imported about four million barrels in August, equivalent to about 134,000 bpd, or half the amount it imported in July.
Bharat Petroleum Corp.'s received about 131,000 bpd Iranian oil in August — a third less than July, the data showed.
Reliance Industries Ltd., operator of the world's biggest refining complex, and Hindustan Petroleum Corp. did not buy oil from Iran in August.
Monthly imports by Mangalore Refinery and Petrochemicals' and Nayara Energy — partly owned by Russian oil giant Rosneft — were little changed at about 120,000 bpd and 138,000 bpd, respectively, the data showed.
In January-August 2018, India's oil imports from Iran were up 21 percent at 600,400 bpd compared with the same period a year ago, the data showed.