Maharashtra and Karnataka states, a leading industry body said on Wednesday.
Maharashtra's sugar production fell to 5.1 million tons from 6.09 million tons, while Karnataka's production dropped 12.7% to 3.1 million tons, the National Federation of Cooperative Sugar Factories said in a statement.
Production in the northern state of Uttar Pradesh rose 14.8% to 4.61 million tons as mills started operations early there, it said.
India has decided to allow mills to divert up to 1.7 million tons of sugar for ethanol production, government and industry officials said last month, as New Delhi aims to reduce disruptions in its ambitious biofuel programme.
With Prime Minister Narendra Modi set to face elections in a few months, India, which is highly sensitive to food inflation, is likely to ban sugar exports, the first restriction on exports since 2016.