"We will be in the alliance with bitterness; won't threaten government with Presidential elections around the corner," Karunanidhi said.
Earlier on Wednesday, DMK issued a veiled threat of pulling out of the alliance on the issue of the "atrocious" petrol price hike, saying the party had never hesitated to do so earlier respecting people's sentiments.
"The DMK is in the coalition. But (being in) alliance is different, but it is our duty to voice concern against policies that will affect the people," DMK chief M Karunanidhi told a large gathering of party supporters to protest against the central government for hiking petrol prices and the state government for increasing bus fares and milk prices.
The 88-year-old DMK patriarch said his party had walked out of alliances, "whether it be the Bharatiya Janata Party-(led National Democratic Alliance) or while being in the VP Singh cabinet."
"We have never hesitated to raise the voice of opposition whenever the basic principles were hurt, and if we cannot solve it by being an ally, we have not hesitated to come out and uphold those principles," he said even as his remarks were loudly cheered by partymen.
Describing the hike as "atrocious", Karunanidhi had said not just opposition parties or UPA constituents, but even Congress leader and Defence Minister AK Antony had expressed dissent over the petrol price hike, saying it was unacceptable.
"Prime Minister Manmohan Singh should take cognisance of this and offer relief to the common man," he said.
Karunanidhi, who demanded a substantial reduction in the Rs 7.50 per litre petrol price hike, said both the Centre and state should vie to win people's goodwill by reducing the burden on them.
"There should be a competition among the two in doing this and they have to vie to win people's goodwill," he said, while recalling that his government had earlier reduced tax on fuel when their prices were hiked.
Targeting his arch-rival and Tamil Nadu Chief Minister Jayalalithaa, Karunanidhi alleged that she was leading an "inefficient cabinet," and that her government was least bothered about people but more on "accumulating wealth."
"The fact that she allows none of the ministers to make statements in the assembly and she does all of them shows she has realised they are inefficient," the five-time former chief minister said.
Slamming Jayalalithaa for hiking the power tariff, he said it was "undue hike for power that is not available."
"The Centre had at least explained the reason for the fuel price hike but Jayalalithaa had not come out with the genuine reason," he said.
Jayalalithaa had justified the hike, saying the government was forced to take the step due to the weak financial situation of loss-making state government undertakings.
The DMK chief also attacked her for spending "huge" amounts of taxpayer money on newspaper advertisements following the completion of one year in office.
Besides Karunanidhi, senior party leaders, his son and DMK treasurer MK Stalin and general secretary K Anbazhagan led the protests elsewhere in the state.