As the police moved forward the crowd broke out into chants of "False-Dmitri out of the Kremlin!" and "Russia without Putin".
'March of Dissent'
The city authorities had refused to authorise the so-called "March of Dissent", saying that the pro-Kremlin Young Russia group had already planned gatherings at every large meeting point in the capital.
Other Russia decided to go ahead with the march and had said it would appeal against the city's decision.
Police vehicles filled the streets around the area as plainclothes security officials helped identify the opposition activists.
Nikita Belykh, the head of the Union of Right Forces, was among those detained.
His party has been particularly vocal in its criticism of Vladimir Putin, who supported Medvedev as his successor.
"Nowadays, every opposition activity is unsafe," Belykh said ahead of his arrest.
"The elections that were held on March 2 can be called a farce... each organisation calling itself liberal or calling itself democratic must be in opposition."
Korneev Yakov, one of the protesters who was waving a copy of the Russian constitution, told Al Jazeera that everyone should be able to gather without risking arrest.
|Korneev Yakov with a copy of the constitution|
"According to the constitution, everybody can meet together without weapons and give their opinion. What does this lead to, you've just seen," he said, referring to the arrests.
"Our democracy, it's right there in helmets," he said, pointing to the security forces that had ringed the square.
Garry Kasparov and Eduard Limonov, two leaders of Other Russia, appeared at another protest in St Petersburg, which officials had allowed to go ahead.
That also took place amid tight security.
Kasparov told the crowd of several hundred: "Now there is very heavy pressure in the country.
"It's important now for people not to be afraid and to understand that it's our city and it's our country."
Maxim Reznik, head of the Yabloko opposition party in St Petersburg, was detained ahead of the St Petersburg protest.
Other Russia said it was organising the protests to allow ordinary Russians to express their thoughts about the political climate in Russia.
Adel Naidenovich, a member of Limonov's National Bolshevik party, asked where the other opposition parties were.
"No Zyuganov here, where is Zhirinovsky," she asked, referring to two of the defeated presidential candidates who have complained about the conduct of the vote.
"We have eight parties not allowed to take part in elections, where are they? There is nobody here because they know that it is fascism, they are afraid of being beaten."