Washington: Even as visiting Pakistan Prime Minister Nawaz Sharif kept up his tirade against India, the US said President Barack Obama had made clear to him that Pakistan should not discriminate among terrorist groups.

"One piece that was important to the President is that Pakistan not discriminate against terrorist groups," White House spokesman Eric Schultz told reporters Friday when asked about Sharif's anti-India comments.

"That's something that we've made clear in the past and was reiterated yesterday in the bilateral meeting," he said referring to the joint statement issued after Thursday's 90 minute meeting between Sharif and Obama.

The joint statement speaks of Islamabad's resolve to take effective action against Pakistan based terror outfit Lashkar-e-Taeba (LeT) and its affiliates responsible for the Nov 2008 Mumbai terror attack - something that Pakistan was unwilling to do in the past.

Specifically on terrorism, Shultz said, Obama and Sharif "both noted that our two countries are threatened by terrorist groups, and that the Pakistani people have suffered greatly."

"These leaders committed to continue bilateral counterterrorism cooperation," he said. "And President Obama highlighted the importance of Pakistan undertaking effective action against terrorists that seek to undermine peaceful dialogue and destabilise the region."

In response to another question, Shultz said, "the President deeply values his relationship with Prime Minister (Narendra) Modi; that the United States and India have worked together very closely."

"They have a strong partnership specifically on expanding economic opportunities. That's something the President has worked hard on," he said.

Obama has "directed his team here at the White House and throughout the administration to focus on our relationship there and seek opportunities to expand cooperation."

Meanwhile, at the State department asked about Sharif's accusation about India's arms buildup and his threat to take countermeasures, spokesman Mark Toner said: "We've been very clear that India and Pakistan need dialogue."

"They need to continue to discuss with each other their mutual concerns about security and that they need greater engagement, because frankly, better dialogue, improved dialogue, greater cooperation between those two countries is important for all the security of the entire region."

Asked to comment on Sharif's description of India-Pakistan relationship as a "most difficult and urgent challenge," Toners said "I'm not going to certainly parse his perception of what he views as the greatest single threat to Pakistan."

But "Pakistan has been, as we all know, deeply affected by terrorism and has taken steps to counter that terrorism in the recent past."

"We want to see those efforts expand. But it's such a complex dynamic. You've got Afghanistan and the Taliban's continued presence there on one side," Toner said.

"You do have tensions with India, and those need to be addressed. We believe that that's best addressed through continued dialogue between the two countries," he said.

"Beyond that, they need to share information, share cooperation," Toner said. "But ultimately, it's up to those two countries to chart a way forward that addresses each of their concerns."

Earlier speaking at a Washington think tank, Sharif accused India of an arms build-up, and said Pakistan will be compelled to respond with counter-measures to retain "credible deterrence". Calling the India-Pakistan relationship a "most difficult and urgent challenge", Sharif also pleaded for greater attention from Washington to Pakistan's "views and interests".

This would be helpful in enabling "Washington to play a constructive role in averting the ever-present danger of escalation," he said.