India has blamed Pakistan for the attack, a charge Islamabad denies, offering to cooperate in an international investigation.
Iran's Foreign Minister Abbas Araghchi has arrived in Pakistan in a bid to mediate mounting tensions between Islamabad and New Delhi following last month's deadly assault on tourists in Indian-administered Kashmir.
Araghchi's visit marks the first by a foreign envoy since the 22 April attack that left 26 tourists dead, a massacre India has blamed on Pakistan.
Tehran has offered to help de-escalate the crisis between the nuclear-armed neighbours.
Pakistan's armed forces remain on high alert after Information Minister Attaullah Tarar cited "credible intelligence" suggesting a potential Indian strike.
Islamabad has denied any involvement in the killings and has offered to cooperate in an impartial international investigation, an offer New Delhi has yet to accept.
Pakistan's Foreign Minister Ishaq Dar, who is set to meet with Araghchi, welcomed Iran's mediation efforts.
Dar said he had held discussions with more than a dozen international counterparts over the past week, including US Secretary of State Marco Rubio and Russian Foreign Minister Sergey Lavrov.
"We will not be the first to take any escalatory step," Dar told reporters in Islamabad.
However, he warned that "any act of aggression by India" would be met with a resolute defence of Pakistan's "sovereignty and territorial integrity."
Dar also accused the Indian air force of attempting to violate Pakistani airspace on 28 April. He claimed Pakistani fighter jets responded by scrambling and forcing Indian aircraft to retreat. India has not publicly commented on the accusation.
Tensions between the two nations, who have fought two of their three wars over Kashmir, have once again boiled over, with both countries expelling each other’s diplomats and nationals, and closing segments of their airspace.
On Monday, Minister Tarar led a group of journalists to Bella Noor Shah, a remote mountain village near Muzaffarabad in Pakistan-administered Kashmir, where India had allegedly claimed the presence of a militant training facility.
Residents told the press they had seen no such camp in the area.
"It is clear there is no truth to the Indian claim," Tarar said.
Also on Monday, Pakistan's military announced the successful test-firing of the short-range Fatah surface-to-surface missile, with a range of 120 kilometres.
The launch was the second in recent days, following a medium-range missile test on Saturday.
The missile was fired from an undisclosed location and, as is customary, was not directed toward India.
Such missiles typically fall into the Arabian Sea or the remote deserts of southern Balochistan.