He is now being shadowed by armed bodyguards and his residence in Mumbai is under police guard, officials said.
Tendulkar, the world's leading scorer in one-dayers with 14,146 runs and a record 39 centuries, is currently in the southern city of Bangalore training for next month's triangular One-day series in Sri Lanka.
Television news channels flashed footage of Tendulkar being tailed by two hulking securitymen.
Sri Lanka will be his first international assignment since the third and final Test against England at Mumbai in March. A shoulder injury forced him out of One-dayers against England at home and then a tour of the West Indies.
The media on Sunday quoted intelligence sources as saying a plan to target personalities emerged during the interrogation of suspects in the Mumbai train blasts which left 183 dead this month and were blamed on Muslim extremists.
"It is a routine alert from the Intelligence Bureau. We have taken care of Tendulkar's security at the hotel where cricketers are staying," senior Bangalore police officer G. B. Chebbi told The Times of India.
The master batsman has been provided with two personal security men and an armed guard around the clock, the official added.
Tendulkar and other top cricketers were also named on a hit-list by an Islamic militant group in 2004, just before India's tour of Bangladesh.
Police have also stepped up security for Bollywood stars Amitabh Bachchan and Shah Rukh Khan, industrialist Mukesh Ambani, and software czars N. R. Narayanamurthy and Azim Premji, media reported.
Indian cricketers face Sri Lanka on August 16 in their opening match of the tri-series, also featuring South Africa.