The 15-minute film will also star actress Neha Sharma.
Shirish, who made his directorial debut with "Jaan-E-Mann" in 2006, feels short movies have more scope to tell edgy stories than full length commercial films, which takes time to make.
"Yes I am making a short film. I decided to do it as I am very much interested in the digital space. Feature films take time to make and then to finally release," Shirish told PTI.
"Short films involve telling exciting and edgy stories. They are also watched a lot today. The length may be less but they have tremendous exposure."
The 42-year-old director said the movie will have an all-film crew working on it to give it a feel of a feature. Interestingly, both Bajpayee and Radhika have featured separately in short films earlier. While the "Aligarh" actor was there in "Jai Hind "and "Taandav", the "Badlapur" actress starred in Sujoy Ghosh's "Ahalya".
Shirish said he cast both of them because he needed strong actors to play the part but the fact that they had done short films did help.
"I needed good actors for the role. Since they had already done short films before so they were open to my idea, the convincing part was easy.
"I had to only approach Radhika because it was Manoj, who had asked me to make it. I am changing gears with this one. I have done lighter stuff earlier but this is intense and dark.
So I needed actors like them who work from the inside and give it their best shot," the director said.
The movie will go on floors by the end of this month and is scheduled to release on April 22.
Shirish is also working on his next feature film which will be a women-centric crime thriller, set in a small town. He last made "Joker" starring Akshay Kumar in 2012.
"The short film is like a prelude to my feature, announcing my ability to make a film in this space. I made a debut in a romantic film so you tend to get stereotyped in that. I am currently in the casting process and in talks with a few people. I need a strong female performer for the role."
The film is scheduled to go on floors in Novemeber as it is set in winter and the directors needs to show snow.
