"The victim has been identified as Dinesh Bhavchandani (39) who has given a statement against Asaram in the case," said the officer.
"The incident took place when Bhavchandani was riding to his house near Vesu Royal Residency. Two men on a bike overtook him and threw acid," she said.
He was taken to a private hospital.
Earlier, two witnesses in cases of rape against Asaram and his son Narayan Sai have been attacked.
A Surat-based woman has accused Asaram of repeated rapes and illegal confinement between 1997 and 2006 when she was living at his ashram on the outskirts of Ahmedabad. Her younger sister has lodged a similar complaint against Narayan Sai.
Asaram (72) is currently in a Jodhpur jail after being arrested in September 2013 for sexually assaulting a minor girl at his ashram there.
Election Results for Lok Sabha Election 2019 will be out on May 23. Get the latest election news and live updates on ndtv.com/elections. Catch all the action on NDTV Live. Like us on Facebook or follow us on Twitter and Instagram for news updates from each of the 543 parliamentary seats for the election 2019