In the notice, they have sought an apology from Bhojwani and Rs 200 crore in damages for defaming them in public with their statements.
Kumar and Banu had in January 2018 lodged a police complaint, accusing Bhojwani of forging title documents of their bungalow worth Rs 250 crore located in Pali Hill area of the upmarket suburb.
On December 21, 2018, Bhojwani had issued a public notice claiming he was the "rightful owner" of the said property.
He had further claimed the 96-year-old thespian was only a "lessee" of the property.
Taking objection to this, Kumar and his actress-wife on December 31, 2018, sent a defamation notice to Bhojwani for misleading the public with false and defamatory statements.
"Bhojwani has damaged the reputation of Dilip Kumar and Saira Banu in public by making false and defamatory statement against them," said the notice sent to Bhojwani by the star couple's advocate Chirag Shah.
"On the basis of forged and fabricated documents, Bhojwani is claiming ownership of a property, originally owned by Dilip Kumar and Saira Banu," the notice said.
It added the actor had already filed an FIR with the city police's Economic Offences Wing (EOW) against Bhojwani and others for criminal conspiracy, cheating and forgery.
"Dilip Kumar and Saira Banu are the legitimate owners of the property situated at Pali Hill in Bandra and have acquired the same in September 1953," the notice said.
The notice further maintained the chargesheet filed by the police in the case against Bhojwani stated that the realtor had claimed ownership of the property on the basis of forged documents.
"Bhojwani issued the public notice on December 21, 2018 with a criminal intention to grab/encroach the legitimate rights of Dilip Kumar and Saira Banu by creating a perception in public that he (Bhojwani) is the owner of the property," it said.