Congress Spokesperson Randeep Singh Surjewala said: "To ask a foreign power to mediate in Jammu and Kashmir by Modi is a sacrilegious betrayal of country's interests."
In a tweet, Surjewala said: "India has never accepted third party mediation in Jammu and Kashmir. Let the Prime Minister answer to the Nation."
The Congress leader's remarks came after Trump on Monday said that Modi had asked him to help on the Kashmir issue and he would love to be a mediator.
Trump said: "I was with Prime Minister Modi two weeks ago, and we talked about the subject. And he actually said, 'would you like to be a mediator, or arbitrator', and I said 'where?', and he said 'Kashmir', because this has been going on for many, many years. I was surprised for how long it has been going on," to which Imran Khan interjected to say "70 years".
"I think they (India) would like to see it resolved, and I think you (Pakistan) would like to see it resolved. And if I can help, I would love to be mediator," the US President said.
The Central government has, however, rebuffed Trump's offer to mediate on the Kashmir issue, saying that Modi had never made such a request to him, and stressed that all outstanding issues with Pakistan are "discussed only bilaterally".
"We have seen the US President's remarks to the press that he is ready to mediate, if requested by India and Pakistan, on the Kashmir issue. No such request has been made by Prime Minister Narendra Modi to the US President," Ministry of External Affairs Spokesperson Raveesh Kumar said in a tweet.
"It has been India's consistent position that all outstanding issues with Pakistan are discussed only bilaterally. Any engagement with Pakistan would require an end to cross-border terrorism. The Simla Agreement & the Lahore Declaration provide the basis to resolve all issues between India & Pakistan bilaterally," he said.
( With inputs from IANS )