In the April 22 attack, the assailants segregated men, asked their names and targeted Hindus before shooting them at close range in the Pahalgam area, killing 26 people, officials and survivors said.
India has identified the three attackers, including two Pakistani nationals, as "terrorists" waging a violent revolt in Muslim-majority Kashmir. Islamabad has denied any role and called for a neutral investigation.
The old rivals, born out of British colonial India in 1947, have unleashed measures against each other after the attack, with India putting the critical Indus Waters Treaty in abeyance and Pakistan closing its airspace to Indian airlines.
Pakistan has said it had "credible intelligence" that India intends to carry out military action against it in the "next 24-36 hours on the pretext of baseless and concocted allegations of involvement in the Pahalgam incident".
India's foreign and defence ministries did not respond to requests for comment.
In a statement, Islamabad said it condemned terrorism in all forms and will respond "assuredly and decisively" to any military action from India.
Indian Prime Minister Narendra Modi has vowed to pursue and punish the Pahalgam attackers.
India's cabinet committee on security (CCS), consisting of Modi and his interior, defence, home and finance ministers is scheduled to meet later on Wednesday, a government source told Reuters.
This would be the second such meeting of the CCS since the attack on April 22.
Modi has told his military chiefs they have the freedom to decide the country's response to the Pahalgam attack, another government source said.
Small arms fire between the two armies has spread to more points along the frontier between the two countries.
The Indian army said it responded to "unprovoked" firing from multiple Pakistan army posts around midnight on Tuesday, the sixth consecutive violation of their ceasefire agreement.
It gave no further details and reported no casualties. The Pakistani military did not respond to a request for comment.
United Nations Secretary-General Antonio Guterres, in separate phone calls with India and Pakistan, stressed the need to "avoid a confrontation that could result in tragic consequences."
The United States has also urged the two to not to escalate tensions. Secretary of State Marco Rubio is expected to speak soon with his counterparts in India and Pakistan.
Britain has called for calm between its Indian and Pakistani communities, and advised against all travel to Jammu and Kashmir, with exceptions.
