"This is an insult of the people of India. You go to a foreign country and humiliate the prime minister," BJP secretary Shrikant Sharma said.
Asked about the opposition's charge that Modi had also insulted past governments on foreign soil, Sharma said BJP welcomed criticism but the prime minister should not be "insulted".
"Political base of the Congress is shrinking by the day. It seems its leaders are hunting abroad for some political base," he said.