The cricketer-turned-politician, in a series of tweets, warned the Indian government that "no force can stop" a nation from achieving its goals when unity is achieved in a freedom struggle and death is not feared.
Tensions have escalated between the two neighbours following India's decision to revoke Article 370 of its Constitution which granted special status to Jammu and Kashmir.
"The fascist, Hindu supremacist (Narendra) Modi government should know that while armies, militants and terrorists can be defeated by superior forces; history tells us that when a nation unites in a freedom struggle and does not fear death, no force can stop it from achieving its goal.
"That is why the Hindutva exclusivist creed of the Modi-led government with its fascist tactics in Indian-occupied Kashmir will fail miserably in its attempt to smother the Kashmiri liberation struggle," he added.
On Wednesday, Khan celebrated Pakistan's Independence Day in "Azad Jammu and Kashmir" (AJK) to express "solidarity with the Kashmiris", while India's Independence Day on Thursday was observed as "Black Day" in Pakistan.
Addressing a special session of the AJK Legislative Assembly in Muzaffarabad, Khan had said the Pakistan Army "is battle-hardened and it is fully ready to respond to any violation by India".
( With inputs from IANS )