In an interview to a private television channel, Khan accused his predecessor of creating a "huge mischief" by attacking the Pakistan Army.
"Nawaz Sharif is playing a dangerous game against Pakistan and I am 100 percent sure that India is supporting him.
"Why Nawaz Sharif always had a dispute with army chiefs, because he was involved in corrupt practices and wanted to control them," he added.
Khan said Sharif is now playing the same game that was once being played by the former founder of the Muttahida Qaumi Movement (MQM) Altaf Hussain, who he said was also working on India's agenda and had his supporters chant 'Pakistan Murdabad' along with calling for India's help to what he called free Pakistan from oppression.
"He (Sharif) is becoming the next Altaf Hussain. He is a coward, I am sure he has support from India. India's interest was to weaken our army. India's think tanks say they want to break Pakistan. Some foolish liberals were agreeing with the narrative of Sharif, who is creating a huge 'fitna' (mischief) by attacking the army," he said.
The convicted former leader, who was allowed to fly to London for treatment late last year, broke his long silence last month, saying that the opposition was up not against "selected prime minister" but against those who had brought him into power in the 2018 elections.
Khan's statement comes after Sharif's speeches to his party members and opposition leaders targeted Pakistan's military establishment for supporting, facilitating and backing the incumbent leader to come in power through rigged elections.
Sharif, during his speech, revealed and claimed that his government, in a bid to soothe ties with the Pakistan Army, back-engineered the US Tomahawk missile to enhance the defence capabilities of the country.
"I have made immense contributions to the army and spent billions and trillions... We made the country a nuclear power and developed JF-17 fighter jet with the collaboration of China," he said in a speech to party members from London via video link.
"Half of the missiles that country's armed forces have were developed during my tenure. Tomahawk missile was developed because of me. We brought it from Balochistan when Clinton had fired missiles into Afghanistan. The Tomahawk missile was found undamaged and reproduced through back-engineering."
Sharif's statements have also prompted the Pakistan Electronic Media Regulatory Authority (PEMRA) to block speeches and statements from being aired by declared absconders, which includes the former premier, who is wanted in cases of corruption of assets beyond means by the country's courts
He was allowed to leave the country on medical grounds by the Pakistan courts.
However, with Sharif looking active in his last two video link speeches, questions are being raised over the credibility of his health condition.
WATCH | Indian Army condemns Pak's campaign, says 'We are secular'