District and Sessions Judge Jawad Abbas of Islamabad said the bail hearing will be conducted on September after he seeks clarification on how the medical examination of the girl, Rimsha Masih, was conducted.
The judge announced his decision after a lawyer representing the man who accused Rimsha of burning pages of the Quran challenged the medical board's report.
The report submitted to the court on Tuesday had stated that Rimsha was aged between 12 and 14 years and that her mental development did not correspond with her age.
The complainant's lawyer demanded that a new medical board should be formed to examine Rimsha. He claimed that legal procedures were not being followed in the case.
The judge issued notices to the government and the complainant over an application seeking bail for Rimsha.
A large number of people, including members of the minority Christian community, civil society groups and international media, gathered at the court for the hearing. Strict security measures were put in place at the court complex.
Rimsha was arrested from the low-income Mehria Jaffar area on the outskirts of Islamabad on Aug 16 after she was accused by an angry mob of burning pages of the Quran.
However, some reports said she had burnt pages of the Noorani Qaida, a booklet used to teach children to read the Quran.
Hundreds of Christian families fled Mehria Jaffar area after her arrest due to fears of attacks by their Muslim neighbours.
When Rimsha was taken to a state-run hospital on Monday for tests, 120 policemen were deployed to guard the facility.
Rimsha's case has once again focused attention on Pakistan's controversial blasphemy law, under which a person can be punished with life in prison or death.
Questions have been raised about Rimsha's age and mental condition. Rights activists have said that Rimsha is a minor and her case should be taken up by the juvenile justice system.
She is currently being held in Adiala Jail in Rawalpindi, where high-profile terrorists like those accused of involvement in the Mumbai attacks have been detained.