The girl was caught in the early hours of December 23 at a staircase -- known as the "Lennon Wall"
-- leading to the Central Government Offices in the city's Admiralty district and was detained by police for 17 hours. They then applied to have the girl taken into care.
But Magistrate Winnie Lau Yee-wan rejected this.
"I can understand why the police made the application," she told journalists outside the court Monday, according to local media. "After reading the social worker's report, I find that it is not necessary to grant the child protection order at this stage."
Reports of the arrest and the care and protection order application attracted widespread criticism among protestors as such applications are usually made by the Social Welfare Department, not the police, and are usually made in cases where a child is at risk.
When an application for a care and protection order is made, the social welfare department is expected to produce a report assessing the needs and the care of the children or juveniles involved.
A spokesperson from the Social Welfare Department told CNN that all court cases in Hong Kong are open, however a court can decide not to disclose information in cases where the identity of a minor needs to be protected.
The spokesperson added that the department's Integrated Family Service Center would continue to monitor the case and provide the appropriate support and services to the girl and her family.
But Gary Tsang, who participated in Hong Kong's pro-democracy street occupations, told CNN earlier this month that the teen was "an innocent political prisoner" and the use of the law in this case was "obviously politically motivated."
The Lennon Wall became a focal point for messages of support for the recent pro-democracy protests in Hong Kong. When the protests were cleared, the messages -- hundreds of post-it notes -- were removed as well.
Protesters started placing notes on the wall as a show of defiance
after police used tear gas on demonstrators at the start of the protest, which led to a two-month occupation of the main road outside the Central Government Office.
The wall was named after the late Beatles star John Lennon and contained messages of support for the protests and references to his song "Imagine."
The girl -- widely known as "chalk girl" -- told local newspaper Ming Pao Daily
earlier this month that she did not regret getting involved with the protests and urged activists not to give up.
Last week, police withdrew an application for a care and protection order for a 14-year-old boy last week. The boy was arrested during the police clear out of the Mong Kok protest site last year. The court file said the boy's parents failed to exercise proper guardianship over him.
A small protest camp outside the Legislative Council still remains and there is a small police presence on the site. Police officers are guarding Lennon Wall and remove all notes posted to it at the end of each day.
Since the protest sites were cleared, demonstrators have resorted to other forms of protest such as the so-called "shopping revolution," which involves protestors blocking the sidewalks and flooding shopping districts every night with yellow umbrellas.
Thirty protest leaders, including the three founders of Occupy Central with Love and Peace and several prominent student leaders, have been called by the police to report to the police headquarters in Wan Chai district, where they could possibly be arrested and prosecuted for their involvement with the two-month long protest.
Hong Kong Police have not responded to requests for comment.