Addressing a public rally in Tiruppur, about 470 km from the state capital Chennai, Modi said, "For us, social justice is an article of faith and not a mathematical formula, the way it is for the opposition parties."
He said it was the NDA government led by Atal Bihari Vajpayee that restored reservation in promotions for the SC/ST, a privilege that was scrapped by the Congress-led UPA government at the Centre earlier.
Referring to his government's decision to provide 10 per cent reservation to the economically backward sections, Modi said the move aims at equality of opportunities to all.
He said the 10 per cent reservation will not affect the existing reservation for SC/ST and Other Backward Communities.
Alleging that the opposition was good at spreading panic and misleading the youth, farmers and other sections of society, the Prime Minister said that for a long time the opposition parties had created tension in society on the issue of social justice.
Modi criticised the Congress' farm loan waiver scheme saying that it would not benefit anybody, but would result in an extra burden of Rs 50,000 crore.
He said for the first time in India's history, his government had announced a Rs 6,000/pa income scheme for farmers' holding less than five acres of land.
When the scheme was announced in Parliament the opposition parties were left shocked, he added.
Modi disclosed that under the farmer income scheme, a sum of Rs 7,50,000 lakh crore would be deposited in banks over the next 10 years.
The PM also announced the setting up of a department for fisheries in Tamil Nadu and laid the foundation stone of a 100-bed Employees State Insurance Corp (ESIC) hospital.
The hospital will cater to the needs of over 100,000 workers and their family members in the hosiery town and nearby areas covered under the ESI Act.
Modi also laid the foundation stones of a new integrated building at Trichy Airport and the new Chennai airport via video conferencing.
To ensure a reliable supply of crude oil to Tamil Nadu and the neighbouring states, the PM also dedicated to the nation Bharat Petroleum Corp Ltd's Ennore Coastal Terminal in Chennai.
He also inaugurated a crude oil pipeline from Chennai Port to Chennai Petroleum Corp Ltd's (CPCL) Manali Refinery in Chennai. The pipeline has been built with enhanced safety features.
Modi also dedicated to the nation a 470-bed ESIC Hospital in Chennai and passenger service on the 10-km stretch of the Chennai Metro Rail -- AG-DMS Metro station to Washermenpet Metro station.
Earlier, Modi flew down from Andhra Pradesh to Tiruppur via Coimbatore. At Coimbatore airport, he was received by Governor Banwarilal Purohit.
The visit met with a black flag protest led by Marumalarchi Dravida Munnetra Kazhagam (MDMK) leader Vaiko.
Vaiko and his supporters were detained by the police as they released black balloons in the sky and shouted "Go back Modi" near the railway station.