The company might consider further investment in the lender subject to pricing, regulatory approvals and required procedures, Mahindra said, adding that the investment will not exceed a 9.9% stake.
Multiple block deals were seen in RBL Bank on Wednesday and the stock ended up 7.1%.
In a separate statement, RBL said it was not aware of any stock purchase by Mahindra.
Mahindra already owns non-banking financial company Mahindra and Mahindra Financial.
An approval from the Reserve Bank of India is needed to acquire a 5% stake in any Indian lender.
($1 = 82.0473 Indian rupees)
(Reporting by Sethuraman NR in Bengaluru; Editing by Sonia Cheema)