The ban is being imposed at the Kumbh Mela, a pilgrimage that has attracted nearly three million people since July.
Authorities say that selfies will be banned on the days that people ritually bathe in the sacred Godavari river.
Organisers say they conducted a study that showed people took too long taking selfies. This slows down the flow of people, leading to pushing and panic.
Signs saying "no selfie zone" can be seen around the two festival sites in the state of Maharashtra.
The festival takes place every three years. It began in mid-July and runs until late September.
The decision was taken after over 100 volunteers conducted a study on behalf of the Kumbhathon group which works with the authorities to help monitor the festival.
"Since 13 July, our volunteers on the field have been collecting data which showed that people stop to take selfies. They also climb to dangerous spots to take selfies," Kumbhathon CEO Sandip Shinde told the Indian Express.
Local official Dr Pravin Gedam told the paper that selfies would only be banned during the "days of the holy dip as we don't want to take away from the festive mood on other days".

Highway police say they found more than 200 large pieces of meteorites hidden under the seats of a truck which they had stopped in a random check.
Three Argentines and a Paraguayan were arrested.
The province of Chaco is world famous for meteorites, which are protected under Argentine law.
Chaco contains an area known as "Campo del Cielo", or the "Field of Heaven".
It spreads out over an area of 1,300 sq km (500 sq miles) and is littered with meteorites which fell around 4,000 years ago.
The largest, named El Chaco, was discovered with a metal detector in 1967 and weighs 37 tonnes.
El Chaco is the second-biggest meteorite ever found - and it too aroused avarice among speculators and collectors.
In 1990, an Argentine highway police officer foiled a plot to steal it for sale to a private US collector.
A "no selfie zone" will be implemented at a major Hindu festival in India due to fears they could cause stampedes.
[NEXT_CONCEPT]
Police in Argentina have arrested four men who appear to have been trying to steal more than a tonne of meteorites in the northern province of Chaco.