Security was heightened in all districts, fearing retaliation from Pakistan.
The Seema Shashastra Bal (SSB) was also asked to step up vigil along the Indo-Nepal border.
Special focus was on security of historical monuments, tourist destinations, public places like railway and bus stations, malls, shopping complexes and film theatres, an official told IANS.
Additional police force was deployed in the peripheral parameters of cantonments in Lucknow, Agra, Kanpur and Meerut, and military installations and airports were put under close watch.
Special checking operations were initiated to screen vehicles on border and other sensitive areas like Maharajganj, Bahraich, Gonda and Gorakhpur.
"Other than scaling up the visible security, we have also sensitised the intelligence system and are keeping an eye on every activity," an official said.
