India warned Thursday any Pakistan military action would be met with "a very, very firm response", a day after New Delhi launched missile strikes in retaliation for an attack it blames on Islamabad.

"Our response was targeted and measured. It (is) not our intention to escalate the situation," Foreign Minister Subrahmanyam Jaishankar said in a speech to his visiting Iranian counterpart.

"However, if there are military attacks on us, there should be no doubt that it will be met with a very, very firm response."

Pakistan Prime Minister Shehbaz Sharif has vowed to retaliate after India launched deadly missile strikes on Wednesday morning, with days of gunfire along their border in Kashmir escalating into artillery shelling.

At least 45 deaths have been reported from both sides of the border following Wednesday's violence, including children.

Jaishankar met Iran's Foreign Minister Abbas Araghchi, who is visiting New Delhi days after visiting Pakistan, as Tehran seeks to mediate between the nuclear-armed neighbours.

Araghchi, in a statement on his arrival in India, said that it was "natural that we want to reduce tensions" between India and Pakistan.

"We hope that the parties will exercise restraint to avoid an escalation of tensions in the region," Araghchi said.