Pakistan says it has refused a request by India's President Ram Nath Kovind to fly through its airspace due to New Delhi's recent "behaviour".
The decision on Saturday comes amid heightened tensions between the two neighbours over the disputed region of Kashmir.
"The Indian president had sought permission to use Pakistan's airspace to travel to Iceland but we decided not to permit him," Pakistani Foreign Minister Shah Mehmood Qureshi said in a statement, without giving further details.
"The decision has been taken in view of India's behaviour."
Such permissions are usually granted. There was no immediate comment by India.
Pakistan closed its airspace to Indian traffic after aerial dogfights in February raised tensions between Islamabad and New Delhi.
It reopened its skies for all civilian traffic in July, ending months of restrictions affecting major international routes.
Both India and Pakistan claim Kashmir in full, but administer separate portions of it. The nuclear-armed South Asian neighbours have fought two of their three wars over the region, and their forces regularly exchange fire across a 740km Line of Control, which is the de facto border.
On August 5, India's Hindu nationalist government led by Prime Minister Narendra Modi revoked a special constitutional status accorded to Indian-administered Kashmir, imposing a communications blackout and deploying thousands of troops to the Muslim-majority state, where a rebellion has been ongoing for 30 years.
Amid a strict lockdown, hundreds of activists and political leaders, including three former chief ministers, have been detained by Indian authorities in recent weeks.
Islamabad responded by downgrading its diplomatic ties with New Delhi in August, expelling the Indian envoy, suspending trade and calling back its ambassador in a deepening row over New Delhi's clampdown in its portion of Kashmir. It also called for the international community to intervene and vowed to take the matter to the United Nations Security Council.
New Delhi insists that the dispute over the territory is an internal matter and has long maintained that it can only be resolved bilaterally with Pakistan.
