Top foreign policy chief Sartaj Aziz, in a press briefing on Jadhav, also asked how "an innocent man" could have two passports.
At the time of his arrest in March 2016, Jadhav had two passports on him, one in his name, and a second in the name of Hussain Mubarak Patel.
"Why was Jadhav using a fake name in his identity documents?' he asked.
Aziz also slammed the "inflammatory statements and rhetoric of premeditated murder" issued by the Indian government, which he said "will only result in escalation, serving no useful purpose".
Aziz said the April 10 sentence on Jadhav was "as per the law of the land.. He (Jadhav) was involved in subversive activities in Pakistan."
He said that India has not responded to a "Letter of Assistance requesting specific information and access to certain key witnesses" that was shared with them on January 23 this year. "There has been no response from the Indian side so far."
Stating that "fully transparent process" had been followed in the sentencing, the top diplomat said Jadhav had the right to appeal within 40 days to a higher court.
Jadhav, who was tried by a military court, could also file a mercy petition with the Army Chief within 60 days of the decision by the appellate court. His last option was to file a mercy petition with the President of Pakistan within 90 days after the decision of the army chief.
He said Jadhav's sentence was based on "credible, specific evidence" proving his involvement in espionage and terrorist activities in Pakistan.
Rejecting Indian contention that Jadhav was a retired naval commander, he said that India had failed to provide any "credible explanation of why their naval commander was in Balochistan".
Jadhav is said to have been arrested in a counter-intelligence operation in Balochistan's Mashkel area.
Aziz said India's lack of cooperation and refusal to provide Pakistan legal assistance in the case were the reasons why consular access had not been provided to Jadhav. India has said it had sought consular access to him 13 times, and was refused each time. On Friday, its 14th request was turned down.
The adviser said Jadhav's "confessional statement" had been recorded before a magistrate and the proceedings were conducted under proper laws.
A qualified legal officer was also provided to defend him in court proceedings, he said.