A wave of protests over the May poll has gripped Malawi since May and a trading outpost west of the capital.
The main roads remained blocked to stop supporters of the ruling Democratic Progressive Party from attending a rally.
The protesters said to be travelling to Mutharika’s first rally in the city since his poll win.
A police man lost his life during the clashes when protesters stoned him to death.
The incident took place in Malawi, ahead of President Peter Mutharika's first public meeting since a disputed election.
Police spokesman James Kadadzera confirmed the incident. "We have lost a police officer," adding that "he was stoned to death and killed by rioters and criminals this morning", said Kadadzera.
A seasoned security expert and retired military man Marcel Chirwa, accused the police of getting embroiled in politics and applying strong arm tactics.
Mutharika also attended a rally in the capital, Lilongwe, a stronghold of the country's largest opposition Congress Party.
There Mutharika stuck to a conciliatory tone, urging the country to unite. "This is our country. Let's not burn it down.” said Mutharika.
Check out our GBS TV blog post for more trending news.