Pakistan’s Prime Minister Shehbaz Sharif told the UN General Assembly on Friday that any attack on the holy cities of Makkah or Madinah would represent a “red line”.
Saudi Arabia’s air defences destroyed a Houthi drone south of Makkah before it entered prohibited airspace over the city last week.
Mr Sharif said any “threat to the safety and sanctity of the Haramain Sharifain”, the two most sacred mosques in Islam, “is a red line that must never be crossed”.
“No Muslim can even dare to think of committing such a heinous crime,” he said.
Pakistan last month signed a joint defence pact with Saudi Arabia and Turkey. The deal, which has not yet been fully ratified, commits to the collective security of Riyadh, Ankara and Islamabad.
Saudi Arabia has similarly declared Makkah off-limits to any aggression.
On Thursday, Saudi state media reported that an urgent meeting is being arranged for the chiefs of staff of Saudi Arabia, Pakistan and Turkey.
The meeting will "explore ways to support Saudi Arabia” under the Makkah Defence Agreement, which stipulates that an attack on one party constitutes an attack on all of them.
The Houthis have intensified attacks on Saudi Arabia amid a wider escalation involving Iran-aligned armed groups in the Middle East.
