Mr Pawar recalled that former prime minister Indira Gandhi was "taught a lesson" by the people (in the 1977 elections) for imposition of Emergency in 1975.
Referring to Union minister Anant Kumar Hegde's remarks, the veteran politician alleged that changing the constitution was the policy of the ruling BJP.
"People will destroy those who attempt to change the constitution. The NCP will fight the battle to remove the ruling dispensation from power. The fight is not easy but we will fight it till the end," the NCP chief said while addressing a party meeting on "Save Constitution".
He said former prime minister Indira Gandhi had worked hard for upliftment of the poor and improved India's prestige at the global level during her tenure.
"However, due to peculiar circumstances, she imposed Emergency in the country. However, the common man taught her a lesson...Not only did her government lose the elections but she herself lost her parliamentary seat," recalled Mr Pawar who was with the Congress before floating the NCP in year 1999.
Emergency, considered as the darkest chapter in Indian democracy, was imposed by Ms Gandhi on June 25-26, 1975. It was lifted 21 months later.
Mr Pawar alleged that atrocities on deprived sections, minorities, women and backward classes have risen in the last four years.
"There are many incidents of mob lynching but the accused are roaming free. The ruling dispensation doesn't believe in the constitution," the former Union minister said.
Mr Pawar also referred to then RSS chief M S Golwalkar's book "Bunch of Thoughts" which he said had termed the constitution "cumbersome and heterogeneous".
Referring to the remarks made by Anant Kumar Hegde, the Minister of State for Skill Development, Mr Pawar said it was the BJP's policy to change the constitution.
Mr Hegde had reportedly said last year that "We are here to change the Constitution and we'll change it."
He later apologised after his remarks invited widescale condemnation.
"Even when union minister Anant Kumar Hegde says that his government's aim was to change the constitution, the government says it was his personal view and there was no such move. There can be no personal view of a union minister.
"This (changing the constitution) is the BJP's policy. The BJP just wants to test the mood of the people by making such comments," Mr Pawar said.
Appealing to his party workers to be wary of the BJP, Mr Pawar said, "Women, backward classes, deprived sections of the society, tribals, minorities will be worst affected if the constitution is changed".
Since the defeat of the BJP in bypolls last month, Mr Pawar has intensified his attack on the Narendra Modi government.
He had appealed to like-minded parties to come together to defeat the BJP in 2019 polls and volunteered to play the role of a unifier.
Get the latest election news, live updates and election schedule for Lok Sabha Elections 2019 on ndtv.com/elections. Like us on Facebook or follow us on Twitter and Instagram for updates from each of the 543 parliamentary seats for the 2019 Indian general elections.