US Secretary of State Mike Pompeo spoke separately with the foreign ministers of India and Pakistan and urged them to avoid "further military activity" following an air strike by India inside Pakistan.

"I expressed to both Ministers that we encourage India and Pakistan to exercise restraint, and avoid escalation at any cost," Pompeo said in a statement issued in Washington on Tuesday.

"I also encouraged both Ministers to prioritize direct communication and avoid further military activity," he said.

Both China and the European Union have also called for restraint. On Wednesday New Zealand's foreign minister Winston Peters also voiced concern over the escalation in tensions.