Victorian authorities say people should not shy away from visiting Melbourne landmarks over the holiday period after four men were charged with planning to bomb popular sites on Christmas Day.

Four men have been charged with preparing or planning a terrorist act over an alleged Islamic State-inspired plot targeting Flinders Street Station, Federation Square and St Paul's Cathedral.

Three men - Hamza Abbas, 21, of Flemington, Ahmed Mohamed, 24, from Meadow Heights and 26-year-old Abdullah Chaarani - were each charged on Friday with one count of preparing or planning a terror attack.

They were among five men taken into custody on Friday after heavily armed police swooped on homes across the northern suburbs that morning.

A fourth man, Ibrahim Abbas, 22, appeared before the Melbourne Magistrates' Court on Saturday charged with the same offence.

All four have been remanded into custody.

Victorian police chief commissioner Graham Ashton says any threat linked to the men's alleged activities has been dealt with.

"I can certainly indicate to the community that through yesterday's investigation ... there is no additional information or criminal intelligence that suggests there is any ongoing threat," he told reporters at Federation Square on Saturday.

"You should feel confident about coming down here as this is a great place this time of year, and people are going around enjoying themselves as they should."

But there will be an increased police presence over the Christmas holiday period, with extra security at the MCG for the Boxing Day cricket test.

"That's not because we have specific intelligence we're concerned about, we just want to make sure that we are playing it safe and keeping the community safe," Mr Ashton said.

"We want people to get out and enjoy themselves this Christmas period."

Premier Daniel Andrews says it's important the community feels reassured that authorities are doing everything they can to help them enjoy the holiday period.

"Every Victorian can be confident that police and their partners are doing everything they can to keep us safe," he said.