The ban was imposed Sunday by self-styled social reformers of Makhnupur village under Pachrukhi police station in Siwan district, 150 km from here.
The decision was taken after three girls - including two cousins - went missing last week. They are yet to be traced.
"A group of villagers issued an order to impose a fine of Rs.10,000 if a girl is found anymore using a mobile phone or wearing jeans and a T-shirt outside her house," a local police official said.
An 11-member committee has been formed to implement the ban.
"Mobile phones, jeans and T-shirts are the cause of all evil in our society, including increasing love affairs and elopement," said Satyender Sharma, a villager.
In the last three months, nearly half a dozen village panchayats across the state have banned girls and women from using mobile phones and ordered them not to wear provocative clothes.