Thackeray said the demand made this week by her father, Satish Salian, who believes she was raped and murdered, and that her death covered up by politicians - "is an attempt to malign" his image.
"We will put forth our side... give our replies in court," he said.
Sena boss and ex-Chief Minister Uddhav Thackeray echoed his son's dismissal, saying: "I was surprised this issue had not been raised so far (in the ongoing Assembly session)... in every session it is raked up. We will represent our side in the court. There is no truth to this allegation."
On Wednesday Satish Salian moved the Bombay High Court seeking a fresh probe into his daughter's death, as well as a FIR against Aaditya Thackeray and others.
He demanded that an inquiry be done by the CBI.
This is not the first time Thackeray has found himself linked to Salian's death.
In December 2022 there were demands made by BJP and Eknath Shinde's Sena faction - that he should face a 'lie detector' test. The response then was - "I don't give a dime..." he told NDTV.