In two televised speeches and a TV interview, Recep Tayyip Erdogan claimed the hundreds of thousands of protesters in 67 cities in more than half Turkey's 81 provinces were manipulated by the opposition Republican People's Party, which he said pushed the demonstrations because it was "unable to beat [the ruling Justice and Development Party] at the ballot box."
The ruling party, known as AKP, started in the tradition of political Islam, but has officially abandoned an Islamist ideology in favor of "conservative democracy," although many critics say the party remains religiously conservative. The opposition party, known as CHP, calls itself social-democratic.
Erdogan also blamed Twitter and other social media for fueling the protests by "a few bums," "looters" and an "extremist fringe."
"There is now a menace, which is called Twitter," he said. "The best examples of lies can be found there. To me, social media is the worst menace to society."
Pictures of riot police attacking unarmed female and elderly protesters with tear gas and water cannons spread across social media the end of last week, galvanizing support for the protest.
The protests started Tuesday as a sit-in by about 50 environmentalists in Istanbul to save the small, tree-lined Taksim Gezi Park from being destroyed so a Las Vegas-type replica Ottoman-style shopping center could be built. The sit-in rapidly snowballed into the largest and most violent anti-government protests that Turkey has seen in years.
The quick growth was fueled in part because social media filled a vacuum created by the lack of coverage by Turkey's mainstream media, many observers said.
The biggest protest Sunday was in Istanbul, a city of 15 million people. An estimated 10,000 people marched into Taksim Square, considered the heart of modern Istanbul. They also marched in neighboring Gezi Park.
Protesters Sunday initially claimed victory after police withdrew Saturday after a heavy-handed response that left hundreds injured, some seriously, many news organizations reported.
But after protesters -- many calling Erdogan a "dictator" -- erected improvised barricades of construction materials and burned public buses near Taksim Square, police Sunday night fired tear gas bombs into the crowds, with the confrontation dragging into Monday, British newspaper The Daily Telegraph reported.
Many protesters had carried supplies of lemons and milk to soothe the tear gas effects, The Wall Street Journal reported.
In Istanbul's Besiktas area, residents leaned from their windows banging pots and pans in support of the protesters, the Financial Times reported.
About 7,000 protesters threw firebombs in the capital, Ankara, and police responded with tear gas. Violent protests were also held in Izmir, on the Aegean coast, and in Adana in the south.
More than 1,000 people were injured in Istanbul during the weekend and 700 in Ankara, the Turkish Doctors' Association said.
Almost 2,000 people were detained, although many were later released, the Interior Ministry said.
"I am not going to seek the permission of [the opposition] or a handful of plunderers," Erdogan said in a televised speech. "If they call someone who has served the people a dictator, I have nothing to say. My only concern has been to serve my country. ... I am not the master of the people. Dictatorship does not run in my blood or in my character. I am the servant of the people."
The White House Sunday night called for all sides in the a key U.S. ally to seek "calm" and appealed to Turkish security forces to "exercise restraint." In a statement the White House also said Turkey's long-term stability was best guaranteed by upholding "the fundamental freedoms of expression, assembly and association."
Taksim Square is the site of a May Day 1977 massacre in which 34 to 42 people were killed and 126 to 220 people were injured.