Dozens of people in the congested Nairobi neighborhoods of Mathare and Kibera engaged police in running battles, throwing rocks and burning tires while officers responded with tear gas.
In opposition leader Raila Odinga's lakeside bastions of Kisumu and Homa Bay in western Kenya, protesters also hurled rocks at police and lit bonfires in the middle of the road.
In the town of Siaya, about 75 km (45 miles) away, the offices of Ruto's United Democratic Alliance (UDA) party were set ablaze, said Cleophas Malala, the UDA secretary general.
The two sides traded blame.
"Raila Odinga is the one who has burnt that office," Malala said.
Dennis Onyango, Odinga's spokesperson, retorted that Malala was engaged in "ethnic profiling" by assuming the attackers were Odinga supporters because they belong to the same ethnic group as him.
Odinga has called for protests every Monday and Thursday, accusing President William Ruto of stealing last year's election and of failing to control the surging cost of living.
The government said on Wednesday that two civilians had been killed and more than 130 people injured, including 51 police officers, in the protests that took place the previous two Mondays.
The international community and religious leaders have called for calm, voicing fears that the violence could degenerate into the ethnic post-election fighting witnessed after the 2007 election that claimed the lives of more than 1,100 people.
"We are deeply concerned by the recent unrest and violence as well as destruction of places of worship and private property," eight foreign embassies, including the United States and former colonial power Britain said in a joint statement Wednesday.
"We therefore call on all leaders and all Kenyans to maintain peace, show restraint, and work toward a swift resolution for the common good of Kenya."
The African Union also appealed Tuesday for calm and political dialogue to put paid to chaos.
On Wednesday, Interior Minister Kithure Kindiki vowed that anyone "irrespective of the political party" inciting public disorder or disturbing the peace would face prosecution.
"The current portrait of anarchy, and the unfolding criminal madness must stop," he said in a statement. "The unfolding situation portends grave danger to the rule of law and the stability of our country."
Protesting Kenyans say they are struggling to put food on the table, battling high prices for basic goods as well as a plunging local currency and record drought that has left millions hungry.
Inflation was running at 9.2 percent in February with food inflation at 13.3 percent.
This report was sourced from Reuters and Agence France-Presse.