Dozens of workers set up plastic chairs and tables in the middle of Lonsdale Street in Melbourne's CBD for their morning smoke break on Friday, forcing the cancellation of trams in the vicinity.

Similar protests also took place on Collins Street and Elizabeth Street in the city centre, as well as in Brunswick, Coburg, Kew, Parkville, South Yarra and Richmond, during the morning and at lunchtime.

The roads have now been cleared.

The action comes after the Victorian government imposed tough restrictions on the industry, with 13 per cent of the state's active COVID-19 cases linked to transmission at construction sites.

From 11.59pm on Friday, tea rooms at sites must shut, and food and drink can no longer be consumed indoors, while travel between Melbourne and the regions for work will be banned.

By the same time on September 23, all construction workers will be required to show evidence to their employer that they have had their first dose of a COVID-19 vaccine.

Limited medical exemptions will apply, in keeping with the vaccine mandate for aged care workers.

Victorian state construction union secretary John Setka said the decision to close tea rooms was "appalling", and was made without consulting the CFMEU.

"It's not really a protest," he told 3AW radio on Friday of the smoko stand-off.

"What they decided was, 'If we can't sit in the smoko shed, where do we have our break?'. So they've taken all the tables and chairs out into the fresh air.

"They've got nowhere else to have their smoko."

But Victoria's COVID-19 Commander Jeroen Weimar said there was a "significant risk of transmission" in tea rooms.

"People are bending over backwards to keep the construction industry going and keep important sites going for important reasons. Please don't," he said.

"We all need to be humble on this and recognise the privileges that those of us who are still able to work can get. If you can't sit next to your mates having a sandwich, that doesn't seem a huge burden to bear."

Opposition spokesman Tim Smith said the construction industry has been "treated abysmally like every other industry has been throughout this pandemic".

"You've now got the CFMEU, as part of the Labor party, protesting against this Labor government, because they're being treated as poorly as the rest of the community," he said.

Premier Daniel Andrews on Thursday said the tightened restrictions were backed by health advice and designed to keep the construction industry open at its 25 per cent workforce cap.

The industry was earlier this week warned it risked losing its authorised worker status amid the launch of an enforcement and vaccination blitz.

In NSW, the entire construction industry was shut down for two weeks as cases escalated.

Australian Associated Press