At least 12 people have been killed and more than 20 wounded in a deadly blast that occurred in the early hours of the morning, AFP reported.
The Jamaat-ul-Ahrar claimed responsibility for Tuesday's deadly blast near the judicial complex in Islamabad's G-11 district.
Two Pakistani security officials told the Associated Press that the blast was carried out by a car bomb.
Pakistani Interior Minister Mohsin Naqvi confirmed the incident, saying the attacker initially tried to enter the court premises, but after failing, targeted a police vehicle.
He accused Afghanistan of carrying out the attack "by Indian-backed elements and representatives of the Afghan Taliban linked to the Pakistani Taliban," although formal investigations are still ongoing.
The blast comes just a day after the attack on a military college in the Vana area and also coincides with another blast in New Delhi's Red Fort; The events have doubled concerns about escalating security tensions in the region.