Victoria's first female Aboriginal MP took to social media on Saturday to share an article by The Age followed by a thread of comments in which she took on those who had sought to "silence" her.

"It's been a tough few days for me, my staff and my family," Ms Thorpe wrote on Twitter.

"To personally receive these threats has shaken every one of us. But I will not live in fear. All too often threats of violence are used as a way to silence women in public life.

"I taught my daughters to stand up to bullies. And that's what I'm doing today. Because I believe I have something to say that matters."

Police were alerted after a man tried to enter Ms Thorpe's electorate office in Northcote on Wednesday afternoon, then slipped an expletive-littered note under the locked door that read that all "black" people should be killed.

An office staff member watched the man walk south along High Street after he left the note.

Ms Thorpe also received several emails threatening her with gang rape.

She said the threats came after she "respectfully asked that we have a conversation" about lowering national flags on January 26 to recognise the "grief and suffering caused to our First Nations people".

"To think that this simple gesture can inspire people to want to rape or kill me is a sign that this pain continues today, and that Aboriginal people cannot and should not 'just get over it,'" she said.

"I know that we are better than this. I know that we are mature enough as a nation to confront our past while walking towards a shared future."

The MP said she was grateful for the community support and Victoria Police and Parliamentary security she received throughout the week.

"It gives me hope that we can come together with compassion and understanding," she said.

The MP's staff alerted the parliamentary security service, who referred the matter to police on Thursday.

Police told Ms Thorpe's office they are attempting to track down whoever sent the emails.

In correspondence to Ms Thorpe's office, seen by Fairfax Media, police said they would increase patrols in the vicinity of the office in response, and offered a security audit of the MP's home.

Ms Thorpe said that the threats had left her feeling physically vulnerable and unable to sleep.

"I walk these streets often and I stop and talk to people ... so thinking that this person is out there and has the confidence to come knocking on my door - then what would that person do if he saw me on the street?" she said.

But she said the threats would not intimidate her against speaking out and that she believed they came from a small, hate-filled element in society.

"My comments are about bringing people together and bringing this nation together, which I think we haven't done a good job of over the years," she said.

Ms Thorpe said publicly this week that Australia Day is "a day of mourning and deep pain for Australia's First Nations people".

"I see the lowering of the flag as an important first step towards truth-telling and healing," she said.

Her call for all Australian flags in Victoria to be flown at half-mast on January 26 drew criticism from Turnbull government MPs, who said the day is one of celebration of all aspects of Australian life, including Indigenous heritage.

Minister for Citizenship Alan Tudge??? told Sky News it was a "ridiculous proposition".

Prime Minister Malcolm Turnbull also condemned calls by Greens leader Richard Di Natale to change the date of the public holiday, which marks the day the First Fleet arrived in 1788.

Last year the government also stripped the cities of Yarra and Darebin of the power to hold citizenship ceremonies after their Greens-led councils voted to stop holding them on January 26.

Aboriginal federal MPs Linda Burney??? and Ken Wyatt have also spoken out about Australia Day this week.

Labor's Ms Burney said the public holiday was problematic, but did not endorse the movement to change the date.

Liberal MP Mr Wyatt suggested the date could be changed after Australia becomes a republic.

An Andrews government spokesperson said it would not fly flags at half-mast this Australia Day, but would "continue to work towards reconciliation through Treaty and self-determination".