Hafiz Saeed, co-founder of outlawed militant organisation Lashkar-e-Taiba, hopes his detention will give a "fresh impetus" to the Kashmiris' "struggle against India".
Saeed, who was allowed to hold a press conference before being detained, also accused the US of orchestrating his arrest.
Accused by India of plotting the 2008 Mumbai attacks, Saeed is also the founder of Jamaat-ud-Dawa, a front organisation of the LeT.
"If someone thinks that placing me under house arrest will help check freedom movement in Kashmir he is living in a fool's paradise. My arrest will give a fresh impetus to the Kashmiris' struggle against India," he said.
Sixty eight-year-old Saeed further said if Indian Prime Minister Narendra Modi thinks that he would get respite in Kashmir after his arrest he is seriously mistaken.
"We have declared 2017 a year of solidarity for Kashmiris," he said adding that all programmes planned for February 5 will be held across Pakistan and PoK.
Saeed was detained yesterday at JuD's Lahore headquarters at Masjid Al-Qudsia Chauburji and was later shifted to his Jauhar Town residence which has been declared as a sub-jail by authorities in Punjab province.
"The government has detained Saeed and four other JuD and Falaha-i-Insanyat (FIF) leaders for 90 days with effect from January 30 but this detention may further be extended on completion of this period if required," an interior ministry official said.
The government may take some further steps against the JuD and its sister organisations in coming days, the official said, adding that the names of several activists of JuD and FIF, a charity run by Saeed, have been placed on Exit Control List (ECL) to stop them from leaving the country.
Saeed has vowed to challenge his house arrest in the Lahore high court.