Rekhaji reportedly walked out of Fitoor due to similarities between her and her role in the film.
However, Abhishek said that the report is not true and people should be cautious before creating such rumours.
"When we started, Rekhaji was doing the film. She is a wonderful, gracious and loving lady. During the course of the film, we saw things differently. We felt that it's best not to do this film together. We can work on something else in the future. But when reports like this come out, it is not fair to her," said Abhishek.
"She is a reserved and private person. She is not going to stand up, say things to safeguard her own interest. We should be cautious. It is downright cruel to say anything about her," added Abhishek.
After Rekhaji left, Tabu was roped in to play the role of Begum and Abhishek was all praise for the versatile actress.
"We are glad that Tabu graciously came on board. This character would have taken months to prepare as it is so layered. We are thankful to Tabu for coming on board in three days and rescue us," he said.
The 44-year-old filmmaker said that he did not make any alterations in the character after the cast was changed.
"The track was not changed. Rekhaji would have done it in her style and Tabu has played it beautifully in her own style. Tabu is like water. You put her in any container and she takes the shape," he added. (Also Read: Katrina Kaif: Rekha's Exit from Fitoor Was Sad)
Fitoor, which also features Katrina Kaif and Aditya Roy Kapur, is scheduled to release on February 12.