MOSCOW — An attempt by Vladimir Putin’s foes to protest his presidential election victory by occupying a Moscow square ended Monday with riot police quickly dispersing and detaining hundreds of demonstrators — a stark reminder of the challenges faced by Russia’s opposition.

The harsh crackdown could fuel opposition anger and bring even bigger protests of Putin’s 12 years in power and election to another six, but it also underlined the authorities’ readiness to use force to crush such demonstrations.

The rally marked a change of tactics for the opposition, which has been looking for ways to maintain the momentum of its demonstrations that flared in December. Alexei Navalny, a popular blogger and one of the most charismatic protest leaders, was the first to suggest that supporters remain on Moscow’s streets and squares to turn up the heat on Putin.

For Putin, the opposition move raised the specter of the 2004 Orange Revolution in Ukraine, where demonstrators camped on Kiev’s main square in massive protests that forced officials to throw out a fraud-tainted election victory by the Kremlin-backed candidate.

The government’s response Monday night was fast and decisive. Lines of officers in full riot gear marched into tree-lined Pushkin Square and forced protesters into waiting police buses. About 250 people were detained around the city, police said.

The crackdown followed a rally that drew about 20,000 people angry over an election campaign slanted in Putin’s favor and reports of widespread violations in Sunday’s voting.

Putin commands the loyalty of police and the military, whose wages were recently doubled. Following Monday’s massive show of force, the urban middle-class forming the core of the protests could be more reluctant to attend future demonstrations.

Navalny, who sought to electrify the crowd with a passionate call of “We are the power!,” was among those detained, along with opposition leader Sergei Udaltsov. Both were released from police custody a few hours later.

“We are calling for peaceful action of civil disobedience, and we shall not leave,” Navalny shouted to the crowd. “We know the truth about this government. This is the government of crooks and thieves.”