Several US lawmakers also condemned the dastardly act.
Seven Amarnath pilgrims were killed and 19 others were injured in a terrorist attack in south Kashmir's Anantnag district on Monday night.
"We consider it to have been a terrorist attack in the state of Jammu and Kashmir in which seven religious pilgrims were killed. That's of great concern to us," the State Department Spokesperson Heather Nauert told reporters at a news conference.
"These were civilians, they were killed as they were exercising their right to worship and that is, in large part, what makes this so reprehensible. That is a great concern to us and our thoughts and prayers go out to those people and to their families as well. Our prayers are with the victims and those who were affected," she said.
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"The terrorist attack on Amarnath Pilgrims is outrageous," said Congresswoman Sheila Jackson Lee. "Religion is a fundamental right and human right #AmarnathYatra #ReligiousFreedom," she tweeted.
Congressman John Ratcliffe in his tweet, sent his prayers to the families of those killed in the "horrific terrorist" attack. Congressman Jim Costa said he is "Deeply saddened at the cowardly attack" on innocent Amarnath Yatra pilgrims. "My thoughts and prayers are with you," he said.
"The terrorist attack on AmarnathYatra is reprehensible and must be condemned," tweeted Congressman Ted Poe. "Our hearts go out to the victims of the terrorist attack on #AmarnathYatra. We must stand united against these deplorable acts of terror," said Congressman John Culberson.
"My prayers are with the victims & their families of this senseless, vicious attack on the #AmarnathYatra pilgrims," tweeted Congresswoman Anna G Eshoo.
In a statement, Overseas Friends of BJP (OFBJP) -USA severely condemned the dastardly attack on the innocent Amarnath pilgrims.
"Indian American community is very sad and shocked to hear this barbaric attack on innocent pilgrims travelling to Amarnath shrine and pray for all victims and their families," said Krishna Reddy Anugula, president of OFBJP-USA.
Chandrakant Patel, immediate past president, said "the Indian Diaspora condemns this cowardly and monstrous attack on the peaceful pilgrims by Pakistan directed terrorists".