Blaming last week's riots in central Myanmar, which have claimed at least 40 lives and displaced thousands of people, on "political opportunists and religious extremists," the reformist president in a 10-minute address on state-run television spoke strongly on the mob violence that have hit Muslims neighborhoods the Mandalay and Pegu regions, The Irrawaddy reported.
"In general, I do not endorse the use of force to solve problems," Thein Sein said. "However, I will not hesitate to use force as a last resort to protect the lives and safeguard the property of the general public," he warned.
It was the president's first public comment on the violence which began March 20 in Meikhtila township. The Irrawaddy quoted the president as saying outside "instigators" were responsible for the communal violence, but no details were available.
"I would like to warn all political opportunists and religious extremists who try to exploit the noble teachings of these religions and have tried to plant hatred among people of different faiths for their own self-interest: their efforts will not be tolerated," Thein Sein said.
"We will take all necessary and effective action to stop their operations in accordance with our Constitution and our existing laws. All perpetrators of violence will be prosecuted to the fullest extent of the law."
The report said Myanmar activists and Muslim leaders also have said the violence appeared to be orchestrated.
Myanmar, formerly called Burma, has been under civilian rule led by Thein Sein since April 2011, after decades of military rule. The Thein Sein government has been credited with a number of reforms and the United States and some Western countries have considerably eased their sanctions on the country.
The isolated Southeast Asian country, however, continues to be wracked by communal violence between the Muslim minority and the majority Buddhists.
The current violence is believed to have been sparked over a dispute between a Buddhist couple and the Muslim owner of a jewelry store in Meikhtila, where Muslims account for the town's 100,000 population, the Financial Times reported. Authorities have arrested about 35 people since the violence.
There were concerns the tensions could to spread Yangon, the former capital previously called Rangoon.
The Times said Min Aung Hlaing, chief of Myanmar's armed forces, earlier this week said the military intended to remain involved in national politics.
Last year, the government had to confront similar communal violence between local people and the Rohingya Muslims in Rakhine state in which dozens died and tens of thousands were displaced. The Rohingyas are not recognized as citizens and some in the government say most of them are illegal migrants from neighboring Bangladesh.
On Thursday, Tomas Ojea Quintana, the United Nations' special representative on human rights situation in Myanmar, urged the Myanmar government to take urgent steps on tackle prejudice and discrimination which he said are fuelling the violence.
"The government must take immediate action to stop the violence from spreading to other parts of the country and undermining the reform process," he said in a statement, adding the military and police "must now be held to account for human rights violations committed against ethnic and religious minorities."
The report said the violence had displaced 12,000 people and left an unconfirmed number of people dead.
The statement reminded that the violence in northwest Myanmar's Rakhine state in June and October of last year had displaced about 120,000 people and left nearly 200 dead.
He also acknowledged Thein Sein's televised address calling for compassion, tolerance, understanding, and empathy among people of all faiths in Myanmar.
At the State Department, spokeswoman Victoria Nuland said the United States supports Thein Sein's call for tolerance and mutual respect, for democracy, for religious pluralism and transparency.
"We note that he did say that he would use force as a last resort if it was necessary to protect citizens," she said. "We underscore, once again, that security measures should protect human rights, not violate them."