RBI banned banks from proprietary trading and Sebi doubled the margin requirement on the domestic dollar-rupee forward trade.
Heightened volatility makes the debt rollovers difficult.
The RBI said it had not found initial evidence of money laundering against the three banks.
The majority view remains for the central bank to leave the cash reserve ratio unchanged at 4 per cent.
India will soon allow corporate houses to open banks despite misgivings within the RBI.
CEO Rana Kapoor said no such discussion or proposition has ever transpired.
An estimated 177 million Muslims in India, the largest Muslim minority population in the world, are unable to use Islamic banks because laws covering the sector require banking to be based on interest, which is forbidden in Islam.