"It is genuine contrition which matters and which should be reflected in a profound and comprehensive apology which alone be a starting point of genuine empathy. Otherwise the country cannot be fooled by gimmickry," party spokesman Abhishek Singhvi said.
Congress leader Mohan Prakash, who is in charge of party affairs in Gujarat, also spoke in similar vein.
"Whatever Modi is doing, only he and god knows. BJP's actions are always full of hypocrisy and stunt," he said.
Buoyed by the Supreme Court order in Gulbarga Society riot case, Modi hit out at his detractors for "defaming" him for the 2002 riots and announced he would undertake a fast for peace, harmony and unity in his state.
"One thing is apparent from the Supreme Court's judgment. The unhealthy environment created by the unfounded and false allegations made against me and government of Gujarat, after 2002 riots, has come to an end. For the past ten years, it has become fashionable to defame me and the state of Gujarat," Modi said in a letter to citizens.
The controversial chief minister and BJP's Hindutva poster boy, who could play a larger role in national politics in the run up to 2014 Lok Sabha polls, insisted those defaming him could not tolerate any positive development of Gujarat.
A senior Congress leader who declined to be identified alleged that Modi's fast was to pressurise the magistrate which will hear the case.