He said there was a "conspiracy" in which the 1999-batch IFS officer was "virtually trapped" and maintained that the diplomat is "innocent" and the US action was unwarranted. "It is not illegality that she is accused of, but the illegality she refused to oblige," he said.
Khobragade was taken into custody on a street in New York as she was dropping her daughter to school. She was released on a USD 250,000 bond after pleading not guilty in court.
The arrest has caused an uproar in India.
India announced retaliatory measures against the United States on Wednesday, including revising work conditions of Indians employed in US consulates and a freeze on duty-free alcohol.
Protests have broken out outside US embassy in New Delhi over ill treatment meted out to Indian diplomat Devyani Khobragade.