The two discussed "global and domestic macro-economic scenario in both countries and regulatory developments", according to an official statement from the central bank.
Mnuchin, who is reportedly on a tour to build support against Iran over the country's nuclear programme, was accompanied by US Ambassador to India Kenneth Juster and Consul General in Mumbai David J Ranz, it said.
The visiting dignitaries met Das and other senior central bank officials, the RBI statement said.
It can be noted that India has had difficulties paying Iran for oil imports during previous rounds of sanctions led by the US, and the RBI had played an important role for solutions in the same.
Mnuchin is also reported to be scheduled to meeting business leaders in the city on Saturday. Details of the same could not be ascertained immediately.