"Pakistan through its consulate in Netherlands came to know that the ICJ ordered India to submit a response by September 13," Dawn newspaper quoted Pakistan's Attorney General Ashtar Ausaf Ali as saying.
Mr Jadhav, 45, was sentenced to death by a Pakistani military court in April.
"The ICJ has written a letter to Pakistan informing us of their decision," Mr Ali claimed.
"India had asked the ICJ to offer it time till December to file pleadings in the Jadhav case, however, the court has dismissed their request," Mr Ali claimed.
"India had adopted the stance that the matter was one of life and death, but Pakistan had stated that the ICJ is not a court of appeals," he said.
Pakistani newspaper Dawn reported that sources privy to the information noted that Pakistan will submit its response to the ICJ in December, while the court proceedings will begin in January 2018.
In a hearing of the case on May 18, a 10-member bench at the The Hague-based ICJ restrained Pakistan from executing Mr Jadhav.
India moved the ICJ against the death penalty on May 8. The next day, the world court stayed the sentence as a provisional measure.
Pakistan claims its security forces arrested Mr Jadhav from Balochistan on March 3 last year after he allegedly entered from Iran. However, India maintains that he was kidnapped from Iran where he had business interests after retiring from the navy.
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