Hafiz Saeed, designated a global terrorist by the US and who has a $10 million bounty on his head, accused minister Khawaja Asif of "slander" according to a legal notice from his lawyer seen by AFP.
Asif, speaking with the dean of the Columbia University School of Journalism Steve Coll in New York last week, was reacting to US President Donald Trump's claim this year that Pakistan was giving safe haven to "agents of chaos".
"We went to hell and we are still burning in that hell... Don't blame us for Hafiz Saeeds, these were the people who were your darlings," Asif said.
"Just only 20 years, 30 years back they were being dined and wined (at the) White House. And now you say go to hell Pakistanis because you are nurturing these -- I don't want to use the word for them," he added, sparking a lively debate on Pakistani social media.
The notice issued by Saeed's lawyer, dated September 29 but obtained by AFP Monday, slammed Asif for the comments and described Saeed as a "patriotic Islam loving Muslim".
"It is shocking to know that (the) Foreign Minister of my country is accusing Hafiz Muhammad Saeed of taking wine!" it said.
"This is abusive language and can never be used about my client," it continued, saying that it was issuing 14 days warning of a defamation suit.
Saeed will seek 100 million rupees ($950,000) in damages, according to the notice.
The horror of the Mumbai carnage played out on live television around the world as commandos battled the heavily armed gunmen, who arrived by sea on the evening of November 26, 2008.
It took the authorities three days to regain full control of the city.
Saeed heads the Jamaat-ud-Dawa (JuD) group, listed as a terror outfit by the United Nations, and considered by the US and India to be a front for Lashkar-e-Taiba (LeT), the militant group blamed for the Mumbai attack.
JuD is also popular for its charity work in Pakistan, where Saaed led a high-profile public life and regularly delivered fiery anti-India speeches as his group operated freely across the country.
He was placed under house arrest earlier this year as Pakistan bowed to foreign pressure.
JuD has lately backed a newly formed political party, the Mili Muslim League (MML), which Pakistan's Election Commission has so far refused to register.
Their candidate contested a recent by-election in Lahore as an Independent, coming third with 5,822 votes.
