The girls, aged between 16 and 18, told the BBC that men often made sexual remarks when they travelled to school in a neighbouring village.
The teenagers said local officials in Rewari district had failed to protect them.
Police have now promised to provide better security for the girls.
The government has also promised to upgrade the existing school in their village to higher-secondary level so they no longer have to commute to school.
But the students, who have been drinking water but refusing food, said that they would not end their strike until they saw written orders.
Some parents and students who are not on hunger strike have also joined the protest.
"Almost every day, we face eve teasing [a local term for sexual harassment]," Sheetal, one of the 13 students, said.
"Should we stop studying? Should we stop dreaming? Are only rich people and their children allowed to dream? The government should protect us or open a higher-secondary school in our village."
Another student, Sujata, said men "often try to touch us inappropriately".
"They write our phone numbers on walls, make nasty comments. Actually much worse happens, but not everything can be described," she said.
Nitin Srivastava, BBC Hindi, Rewari
It's been a harrowing week for these girls as they demand better schooling options and safety. Their parents have also been protesting, putting aside their farm work and daily jobs.
Haryana is one of the most backwards states in India in terms of gender ratio, and crimes against women are not uncommon.
But this is probably the first time that young girls have decided to protest. They have found strong support from their community, including men who admit that women need to be treated equally.
The mother of a protesting student said it was "painful to see these girls suffer".
"These young girls face the kind of harassment that I can't even describe. When we complain to the police, they put pressure on us to take such cases back," she said.
Rohtash Kumar, the father of a protesting girl, said the problem of harassment had existed for years.
"It's the first time that girls have taken the matter in their own hands. The men in our village support their struggle," he said.
He wants to see concrete assurances that changes promised by police and local officials will be implemented.
"Such promises have not been fulfilled in the past. We want to be sure that our struggle doesn't go waste because of a false promise," Mr Kumar added.