Putin said the opposition movement was too disjointed and that he did not even know which of its speakers attended a rally Saturday that became the largest ever show of discontent at his 12-year domination of public life.
"I do not even know who spoke there," Putin said in televised comments. "Do they have a common platform? No. ... Is there anyone to talk to? We need to discuss all of their issues, their problems, but this requires some sense."
Saturday's second demonstration was both larger and more directly focused against Putin than a December 10 protest called in response to a fraud-tainted parliamentary vote won by his ruling party.
Protesters are planning a new event in defence of "political prisoners" on a central Moscow square Thursday that could attract hundreds of people but has not yet been approved by the city authorities.
"We were never against dialogue with the opposition," said Putin. "But we are against one thing -- we are against any expression of extremism. It has to be strictly prevented."
The nascent movement is being led by a new generation of politically-active Russians such as the anti-corruption blogger Alexei Navalny and several other young activists who spent time in jail following protests this month.
"Good for him," Putin said flatly when asked what he thought of Navalny as a protest leader.
"They have other leaders. But he is probably one of them."
The comment appeared to be Putin's first on a man who is quickly emerging as a rising star among younger Russians who now pose the main challenge to the country's tightly-controlled political system.
Analysts said the protests had stunned some Kremlin insiders and speculation had mounted that Putin may simply assume President Dmitry Medvedev's role early after they previously agreed to swap jobs after the March 4 vote.
"We have not discussed this," Putin said of the idea of him becoming acting head of state. "There is no need for this."
But Putin also hinted that he may skip the televised presidential debates that traditionally precede elections because his opponents had no record to stand on.
"It is not that I am afraid," said Putin. "The problem is that the opposition is not responsible for anything."
The number of candidates who will face Putin grew to three Wednesday after election authorities registered Communist Party leader Gennady Zyuganov and the flamboyant ultra-nationalist Vladimir Zhirinovsky.
The central election commission had earlier registered Putin -- the first candidate to win the honour -- and former upper house of parliament head Sergei Mironov of the left-leaning A Fair Russia group.
All three of his rivals were beaten badly by Putin in previous elections and none is expected to pose a serious challenge to a leader who has remained Russia's most popular politician for more than a decade despite his recent dip in support.
The established political parties represented in the State Duma are not fully involved in the protests, whose leaders like Navalny come from a wide range of backgrounds.
Yet the protests that have shaken Putin's once-invincible image could make his likely third term more difficult than his first stretch as president from 2000 and 2008.
Russian newspapers reported that Putin was personally responsible for the sidelining Tuesday of top Kremlin strategist Vladislav Surkov, who designed Russia's tightly-controlled politics and did not avert the demonstrations.
"Surkov has his vision of the development of events after the mass meetings and his opinion differs from that of Putin's circle," the Vedomosti daily quoted a source in the Kremlin administration as saying.