"I and DMK party led by me would like to have a secular government at the centre," Karunanidhi told reporters.
He said the two communist parties - the CPI and CPI-M - have not approached his party for an alliance.
The two communist parties recently announced their exit from the alliance with the ruling AIADMK.
The DMK has fielded eight of its sitting Lok Sabha members while the others are new faces.
Of the 40 constituencies (39 in Tamil Nadu and one in Puducherry), the DMK has allotted five seats in Tamil Nadu to its four allies.
The party has retained 2G scam tainted A. Raja and Dayanidhi Maran as its candidates. They will contest from Nilgiri and Central Chennai constituencies.
The other sitting Lok Sabha members of the DMK who have been retained are T.R. Baalu, T.K.S. Elangovan, S. Jagathrakshkan, R. Thamaraiselvan, Gandhiselvan and A.K.S. Vijayan.
Karunanidhi's eldest son and former union minister M.K. Alagiri has decided not to contest the Lok Sabha polls.