Some protesters scuffled with police who banged their clubs against plastic shields.
Five protesters were arrested at a seperate march on Friday.
Avi Lewis, Al Jazeera's correspondent covering the protests, said many were angry at the money spent on the summit.
"One of the flash points has been the cost of the summit itself, it sparked a tremendous amount of outrage here in Canada, " he said.
"A recent poll showed that 78 per cent of Canadians thought the cost of the summit was unacceptable."
Security for the G8 and G20 summits has cost Canadian tax payers more than $1bn.
"In the last two G20 summits in Pittsburgh and London, the combined security cost was $25 million.
There is a feeling on the streets that this could be the most expensive and wasteful photo-op in the history of humanity," our correspondent said.
Liisa Schofield, a protest organiser, said that money spent on the summit should have been been used to provide shelter for homeless people.
"There is 10,000 people who live on the streets of Toronto and there are 70,000 people on the waiting list for social housing."
The money the Canadian government has decided to spend on this summit "could have paid for all 80,000 people who are currently without proper housing to live in a proper apartment for a year," she said.