"I'm sorry for what happened with that woman," said Joaquim Fernando, one of around 100 protesters at the scene. "I don't agree with a brutal act like that. Every citizen has the right to demonstrate," the 26-year-old told AFP.
"We demand that Venancio Mondlane be our president because that's who we voted for," said another protestor, Olavio Jose, 24.
Rights groups have accused police of killing dozens of people in post-election protests after the authorities said Frelimo's Daniel Chapo got 71 per cent, far ahead of Mondlane's 20 per cent of votes.
The Centre for Democracy and Human Rights, a local civil society group, told AFP last week it knew of 65 people killed in police operations against the demonstrations.
Human Rights Watch said Monday that Mozambican security forces killed at least 10 children and injured dozens more.
President Filipe Nyusi, who is due to step down in January, said in a State of the Nation address on November 19 that 19 people had died, including five police officers.
Protesters also blocked trucks at Mozambique's main border post with South Africa for most of Wednesday, according to the South African border authority.
The crossing, a key link for exporters using Maputo's Indian Ocean port, has been closed several times by protests over the past weeks.