The incident was reported from southeast Delhi's New Friends Colony.
The girl was allegedly kidnapped on May 10 when she had gone to buy ice cream, they added.
The girl's father, who works as a driver with the Army on a contractual basis, alleged that his daughter was kidnapped by a group of 16-17 men who lived nearby. They immediately went missing after his daughter was kidnapped.
Their landlord had rented out the room without verifying their antecedents, her father told PTI.
For two months, the police conducted several raids in Etah and Hathras in Uttar Pradesh but to no avail. In the meantime, the girl's father approached the Delhi High Court.
"I used to drive to places along with the police but even though we found some clues to my daughter, there was no success in tracing her. The police even cast aspersions on my daughter's character which was quite hurtful, he added.
"I approached the Delhi High Court to direct the police to trace my daughter immediately. The court asked the police to produce my daughter as soon as possible," he said.
During their probe, the police also found one 'nikahnama' which stated that the girl had been married off to someone on July 3.
On July 7, the man whom the girl had been married to, surrendered in the Saket Court along with her. She was medically examined and found to be three weeks pregnant, police said.
However, she did not want to stay with her parents so she has been put up in a shelter home, they added.
Her 'husband' and another witness to the marriage have been arrested and are currently in judicial custody.
Her father said that he spent Rs 47,000 in helping the police trace his girl.
"I spent money on travel, food and fuel while I travelled with the police personnel to Etah and Hathras. I must have spent around Rs 47,000 on travel," he alleged.
Romil Baaniya, Deputy Commissioner of Police (Southeast) said that an inquiry has been ordered into the father's allegations about being asked to pay for the travel expenses.