The fatwa, or religious order, was issued after a series of bomb blasts rocked the Hindu holy town of Varanasi last week, killing 20 people.
It was announced on Monday by the Darul-Ifta Firangi Mahal in Lucknow, a well-known Muslim seminary.
Whatever the faith, attacks on religious shrines are forbidden by Islam, according to the fatwa, which called such attacks "one of the biggest crimes against humanity".
"The Prophet Muhammed has given clear directions that proper protection should be given to the religious places of other communities," said Maulana Khalid Rashid, the seminary's head cleric on Tuesday.
"The people who attack (Hindu) temples in the name of religion are doing a disservice to Islam. This is an anti-Islamic act."
A number of social organisations have asked Muslim clerics to speak out against the attacks in Varanasi.
The edict was issued after the
bombings in Varanasi
Police have said there are strong indications that Muslim militants based in the troubled Himalayan region of Kashmir were responsible for the attacks.
More than 80% of India's billion people are Hindu, while Muslims are the country's largest religious minority.