Sixty-two of the infections were linked to known cases, health authorities said.
Of the 270 COVID-19 patients in hospital, 40 people are on a ventilator. Eighty-seven per cent of patients were unvaccinated.
Victoria has 4,974 active coronavirus cases.
Health Minister Martin Foley said the health system is under more pressure.
"It (case numbers) doesn't indicate the system is overwhelmed, but the system is clearly under pressure," he said.
"We have learnt a lot over the last 20 months but dealing with several thousand active cases is more challenging than single or double-digit cases."
He said the reproduction number, which indicates on average how many people the virus spreads to from each confirmed COVID-19 case, has been falling over the last week from 1.5 to 1.4 or 1.3.
"It (reproduction number) will continue to head down by ensuring Victorians follow the rules. Make sure you get vaccinated; and get tested early and quickly."
He said the "whole (construction) sector needs to smarten up" after a number of cases emerged on construction sites. Mr Foley warned further restrictions for the sector may be implemented.
Health department deputy secretary Kate Matson said contact tracers would be prioritising phone calls to the highest risk individuals.
"We will also be moving to make phone calls first based on risk, so there may be some delays later this week in the time between you receiving a text message and you getting that call."
Most of the new cases were recorded in the northern suburbs - over 2,500 - representing 55 per cent of the caseload.
"Craigieburn is one of the most serious situations, in terms of case numbers," Ms Matson says.
"From yesterday's numbers, it is more than double the next suburb, being Roxburgh Park, of 28 cases."
Some 2,000 officers deployed in biggest police operation in 20 years
The numbers come as police embarked on their biggest operation in two decades to prevent protesters gathering in breach of public health orders.
The city's CBD will effectively be turned into a no-go zone for Saturday's rally, with most public transport to and from the precinct suspended and a "ring of steel" erected around its fringe.
Authorised workers and those with COVID-19 vaccination bookings at two city-based hubs were required to show proof to board limited buses and pass through checkpoints from 8am to 2pm.
The partial public transport shutdown was made at the request of police after 4000 people attended a violent anti-lockdown protest on August 21.
Some 2,000 officers were deployed during Saturday's operation, which involve road checkpoints, barricades and roving patrols.
Chief Commissioner Shane Patton labelled it the biggest Victoria Police operation since the 2000 World Economic Forum was held in Melbourne.
COVID-19 restrictions eased
Meanwhile, Melbourne and Ballarat residents were granted modestly eased COVID-19 restrictions after reaching 70 per cent first dose coverage across Victoria's eligible population.
Among the changes, people will be able to meet one person from another household for a walk or picnic, outdoor exercise time is doubled and the travel limit expanded to 10km.
Fully vaccinated adults can see five people from two households, plus dependants for a picnic.
The state government is planning to outline a full roadmap out of lockdown on Sunday, tied to double dose vaccination rates and based on Burnet Institute modelling.