Sources in the Home Ministry said the explosions in the city's Dilsukhngar were a terror strike by "a well-trained" group which timed the explosions to cause the maximum damage.
Intelligence agencies had reportedly not picked up any alerts of a possible attack in Hyderabad.
Security has been stepped up in sensitive areas, and railway and bus stations in major cities. A senior Delhi Police official said security personnel have been alerted and they were keeping a tight vigil on the city.
"We are always on alert. There is nothing to panic," the official said.