A week after a deadly terrorist attack in Kashmir, diplomatic efforts to ease rising tensions between India and Pakistan have ramped up, as global jitters grow over the possibility of a military confrontation between the nuclear-armed neighbors.

On Wednesday, Secretary of State Marco Rubio held separate conversations with Prime Minister Shehbaz Sharif of Pakistan and the Indian foreign minister, S. Jaishankar.

In his exchange with Mr. Jaishankar, Mr. Rubio “reaffirmed the United States’ commitment to cooperation with India against terrorism” but also encouraged New Delhi to work with Pakistan to “de-escalate tensions and maintain peace and security,” the State Department said in a statement.

Mr. Rubio took a more pointed tack with Mr. Sharif, emphasizing the “need to condemn the terror attack” while urging Pakistan to work with India, according to the State Department.

Shortly before that conversation, senior Pakistani officials condemned the attack during a news conference. But they added that India, which said last week that the attackers had “cross-border linkages,” had provided no credible evidence of Pakistani involvement.