Apart from its embassy in New Delhi, the United States has four consulates in Mumbai, Kolkata, Chennai and Hyderabad.
The five US diplomatic missions are considered 'high risk' category buildings and are being provided round-the-clock security including monitoring of ingress and egress of every individual.
The directive to beef up security has come in the wake of American ambassador to Libya Christopher Stevens and three other embassy staff being killed in the eastern Libyan city of Benghazi.
They were killed when protesters angry over a film deemed offensive to Islam attacked the American consulate there last night.
The Benghazi incident followed a protest in neighbouring Egypt where protesters surrounded the US embassy in Cairo, some of them climbing up the walls and tearing down the American flag, to protest the film.