Clinton, however, commended the steps taken by India so far in lowering purchases of Iranian oil.
"India is certainly working towards lowering purchases of Iranian oil. We commend the steps they have taken thus far. We hope they will do even more," she told a public event in Kolkata on the first leg of her visit to India that will also take her to Delhi.
Clinton's remarks came when she was asked why the US wants India to reduce oil imports from Iran when India is not an oil producing nation.
The US' top diplomat also said there was adequate oil supplies available from countries like Saudi Arabia. Pressing India to further reduce oil imports from Iran tops the agenda of Clinton who flew into Kolkata yesterday at the start of a three-day visit to India.
The US has been urging India and other countries to slash oil imports from Iran aimed at stepping up pressure on Tehran to comply with international demands over its nuclear programme.
Clinton said it could be "devastating" for the world if Iran developed a nuclear bomb. She said that Iran has been regularly flouting international obligations especially its insistence on nuclear proliferation.
"The international community feels that Iran has to be pressurized into changing its behavior, and it is this pressure that has convinced Iran to come back to the negotiating table," she said.