The accused wanted to get Kareena's personal mobile number so he hacked her IT account, they said.
Kareena's chartered accountant had last year approached the police with the complaint that somebody had hacked her IT e-filing account and tampered with it.
Cyber-police tracked down the culprit today.
The accused files income tax returns for people as a part-time job while working with paramilitary forces, police said, without disclosing his name. Further probe was on.