Earlier in the day, the Supreme Court acquitted Aasiya Bibi, a Christian woman condemned to death on blasphemy charges, after accepting her 2015 appeal against her sentence.
Bibi has always denied blaspheming.
Approximately 40 people are believed to be on death row or serving a life sentence in Pakistan for blasphemy, according to a 2018 report by the United States Commission on International Religious Freedom. "Pakistan's Supreme Court must be appreciated that it upheld the law of the land and didn't succumb to any pressure".
An argument ensued, and Bibi was reported to a Muslim cleric five days later for her supposed blasphemy. The judgements of the High Court as well as the Trial Court are reversed. In their ruling, the justices pointed out that her alleged confession to the crime was given while a crowd was "threatening to kill her".
"They are inciting you for their own political gain, you should not get trapped by them for the sake of the country, they are doing no service to Islam", Khan said.
"These protesters are not "protecting" Islam; they are just trying to fill their vote banks. To the faction making these threats, I am telling you do not take the state on". Dozens have been killed following blasphemy claims, sometimes by mobs of men.
At least 74 people have been killed in violence related to blasphemy allegations since 1990, according to an Al Jazeera tally.
The landmark Asia Bibi case has already set off violent protests by hardliners who support strong blasphemy laws.
People listen to Khan's address in Pakistan.
In Islamabad, hundreds of protesters gathered to block the main Faizabad highway interchange, a key entry point into the city.
"This (PTI) government has done against blasphemy which no other government could do, when a Dutch MP announced to exhibit blasphemous caricatures, we raised our voice on all forums and then the Dutch MP had to withdraw his announcement", said Imran Khan.
With a riot-like situation slowly building in Pakistan after the Asia verdict, it might prove to be challenging for the Imran Khan government who had validated the blasphemy laws during his election campaign.
Another person saw her drinking water from a cup that had previously been used by Muslims and informed Bibi that it was not proper for a Christian to use that cup, as she was unclean.
Her case has outraged Christians worldwide and been a source of division within Pakistan, where two politicians who sought to help Bibi were assassinated. Her family, who have lived in hiding for years due to the security threats, were not present in the courtroom. He said they need to continue praying for their nation.
BBC News reporter Secunder Kermani, on the ground in Islamabad on Wednesday, wrote, "Asia Bibi's lawyer, closely flanked by a policeman, told me he was "happy" with the verdict, but also afraid for his and his client's safety".
"The most important thing in the universe is the honour of the Prophet Muhammad ... everything else is secondary to this", said Muhammad Zaman, 30, a government employee who joined the TLP's blockade of a major motorway into Islamabad.
Asad Hashim is Al Jazeera's digital correspondent in Pakistan.