The victim, a mass communication student, got four stitches on her head, they said.
A case of criminal assault and outraging modesty of a woman has been registered in connection with the incident but no person has been arrested yet, police said.
The complainant alleged that when she and her friends approached Amar Colony Police Station to lodge a complaint, some officials there convinced them not to register a case and sent them back, a charge denied by police.
"However, when the victim approached police today again, the case was registered immediately on the basis of her complaint," Joint Commissioner of Police (Southeast) R P Upadhyay said.
In her complaint, the woman told police that the incident took place on the wee hours yesterday. She and two of her friends, one female and the other a male, had just returned home from a party and went downstairs to the parking area again to fetch a mobile phone from their car.
During the fight, one man from the other group attacked the woman with a beer bottle and she started to bleed. She along with her friend then went to the police station to report the incident, from where they were sent to AIIMS for medical treatment, police said.
The accused had also returned from a pub in Greater Kailash area and have claimed that they were not consuming alcohol on the road, police added.
One woman and a male from the accused group also approached police this evening and they claimed that the fight started only after the complainant's male friend passed an objectionable remark on her, police said.
The case is being probed from all angles, Upadhyay added.
