Kejriwal had alleged the Zakir Hussain Memorial Trust, run by Khurshid and his wife Louise, embezzled Rs. 71 lakh meant for the disabled.
India Against Corruption has threatened a protest in Khurshid's constituency Farrukhabad in UP on November 1.
Soon after the sting, the minister had found himself in more hot water over his comments, "I have been made law minister and asked to work with the pen. I will work with the pen, but also with blood", and "let them come to Farrukhabad. But let him also return from Farrukhabad".
The remarks were interpreted as a threat to Kejriwal and the chorus for Khurshid's resignation got louder.
The Congress was quick to disapprove the remarks.
Earlier too, Khurshid had faced criticism from within the party for his statements - one of them earning him a censure from the election commission - during the Uttar Pradesh assembly polls.
But on Sunday, the party chose to stand by him.
"The corrupt are not just protected but also rewarded," Kejriwal tweeted.
"Salman was law minister and has been made foreign minister. Does that mean he has failed as law minister or that he did so well that he was made foreign minister? The country won't benefit from it."