Jadhav, 46, was awarded death sentence by military Field General Court Martial under the army act for his alleged involvement in terrorism and espionage. The death sentence was confirmed by powerful army chief Gen Qamar Javed Bajwa.
Speaking in the Senate, upper house of parliament, the defence minister today said that Jadhav has the right to appeal against his death sentence within 60 days.
The sentence sparked angry reaction from India which said Jadhav's execution would be treated as "premeditated murder."
Asif dismissed Indian concerns that proper legal process was not observed in the trial. "There was nothing in the [legal] proceedings that was against the law," he said.
He also rejected the charges of premeditated murder.
"It's not premeditated murder, what's happening in Kashmir is (premeditated murder)," he alleged.
The minister further said that the trial of Jadhav went for went on "for three months", rejecting rumours that he was hastily convicted.
The minister said those working against the security of Pakistan would be treated with "iron hands."
"Whether the enemies come from across the border or within Pakistan, they will receive punishment," he said.
He said that Jadhav had confessed his crime in the confessional statement, which is available on record.
Pakistan claims its security forces had arrested Jadhav from the restive Balochistan province on March 3 last year after he reportedly entered from Iran. It also claimed that he was "a serving officer in the Indian Navy."
The Pakistan Army had also released a "confessional video" of Jadhav after his arrest.
India had acknowledged that Jadhav had served with the navy but denied that he has any connection with the government.
The incident is expected to further deteriorate already strained Indo-Pak ties which were hit after deadly attacks in Pathankot and Uri by Pakistan-based terrorists last year.
Govt to do "everything possible" to get justice for Jadhav: Rajnath Singh
The government will do everything possible to get justice for Kulbhushan Jadhav, who has been handed down death sentence by a Pakistan military court, Home Minister Rajnath Singh said.
While condemning the action, Singh said in the Lok Sabha that Pakistan had ignored all norms of law and justice.
"The government strongly condemns it. All norms of law and justice were ignored. I want to assure the House that the government will do everything possible to get justice for Jadhav. He will get justice," he said.
EAM Sushma Swaraj warns of consequences on diplomatic relations
External Affairs Minister Sushma Swaraj made a statement in both the Lok Sabha and the Rajya Sabha, asserting that India will go "out of the way" to ensure justice to Jadhav who is an "innocent kidnapped Indian".
Jadhav's execution will be taken by India as a "pre-meditated murder" and Pakistan should "consider its consequences" on bilateral relations, if it proceeds on this matter, Swaraj warned.
She said the charges against Jadhav, who was doing business in Iran and was kidnapped and taken to Pakistan, are "concocted" and the trial against him was "farcical", leading to an "indefensible verdict".
"Let me state clearly that the government and the people of India would view very seriously the possibility that an innocent Indian citizen is facing death sentence in Pakistan without due process and in violation of basic norms of law, justice and international relations," she said.
"There is no evidence of wrongdoing by Jadhav. If anything, he is the victim of a plan that seeks to cast aspersions on India to deflect international attention from Pakistan's well-known record of sponsoring and supporting terrorism."
Pak army court sentenced Jadhav to death
Pakistan military court has sentenced Indian national Kulbhushan Jadhav to death after he was convicted of "espionage and sabotage activities", prompting New Delhi to warn Islamabad that it is a case of "premeditated murder".
The trial proceedings that led to the capital punishment for Jadhav were also described by India as "farcical".
The award of the death sentence to the 46-year-old former Naval officer at a court-martial was confirmed by Pakistan's army chief Gen Qamar Javed Bajwa today and is expected to further deteriorate already strained Indo-Pak ties that were hit after the deadly attacks in Pathankot and Uri by Pakistan- based terrorists last year.
The court martial was closed to the public and consular access was not provided to Jadhav.