According to various polls, about 90 percent of Russians oppose the plan to raise the retirement age, and a recent poll by the Levada Center polling agency found that more than 50 percent of Russians say they would participate in protests against it.
It said 129 were held in the Urals city of Yekaterinburg, 60 in the southwestern city of Krasnodar, and 48 in Perm in the Ural Mountains.
The United Russia party recorded its worst performance in regional elections in more than a decade as voters registered their anger over a controversial reform set to raise the state retirement age and economic conditions deteriorating under Western sanctions.
United Russia also suffered defeats to the Communists in party-list votes for three regional parliaments.
Russian President Vladimir Putin, who is 65, has said that the pension age should be raised to 60 for women and 65 for men to address the increasing burden on the pension system.
News reports and tallies from the OVD-Info organization that monitors political repressions showed at least 40 arrests connected with the protests elsewhere, including 12 each in the cities of Khabarovsk and Tomsk. Vladimir Chernikov, the head of Moscow region security, said that the demonstrators "failed to cause a provocation" but "spoiled the mood" of residents celebrating the annual City Day weekend.
"I can't keep being afraid anymore", she said of her decision to risk detention by showing up at a protest in Moscow's Pushkin Square that attracted several hundred people.More news: Fuel price hike: Bring petrol under GST to arrest surge, say experts
Demonstrations also took place in Saint Petersburg and Moscow on Sunday afternoon.
The proposals have been heavily criticised by Russia's usually subservient press, with Moskovski Komsomolets, a popular Moscow newspaper, describing them as the "most unsafe and risky reform of President Putin's 20-year rule". Navalny said the move was created to derail the protests which took place in 80 towns and cities, including Moscow and St Petersburg.
Navalny's group said its St. Petersburg coordinator and another of its activists were detained in St. Petersburg as well.
Thousands of Russians turned out to protest deeply unpopular pension reforms on Sunday as the country voted in local elections.
Sobyanin's supporters say he has transformed Moscow with billion-dollar renovation projects that include a showpiece central park and new pedestrian areas along with a string of new metro stations.
In advance of the vote, a Moscow court jailed Navalny for 30 days, just a couple weeks before he planned to stage a rally on election day.