The warning says that foreign militants, possibly from al-Qaida, may be plotting to set off bombs at airports, Indian government offices or places where crowds may gather. No other details were given.
"The point of it is to alert Americans to this possible threat, and to encourage Americans to maintain a low profile over the coming days," said David Kennedy, the embassy spokesman.
Tensions are high in India after it emerged that neighboring Pakistan arrested suspects connected to the plot uncovered in London to blow up U.S.-bound airliners.
Indian authorities are especially vigilant about possible attacks every August, in the lead-up to the country's August 15 Independence Day. India is the frequent target of terrorist attacks by Islamic militants opposed to India's control of part of the Kashmir region.