The warning follows the arrest of six protesters yesterday at London Concrete in Bow.
Protesters from Extinction Rebellion chained themselves to the gates of the plant in east London preventing deliveries to and from the site.
They were protesting about construction of the nearby Silvertown Tunnel and the environmental impact of concrete.
Eleanor McAree, 25, from Extinction Rebellion Tower Hamlets, said: “Concrete has a huge environmental impact and building another tunnel will only make air pollution across East London worse. The air pollution is already at dangerous levels and is affecting the health of children and adults in the area.”
The group is planning protests all this week as part of its “Summer Rebellion” with construction a key target.
The Metropolitan Police said: “In the early hours of Tuesday morning, protestors congregated at the entrance of the construction site which prevented companies within the area from being able to go about their daily business.
“As a result, a total of six people – three men and three women, aged between 30 and 67 – were arrested on suspicion of aggravated trespassing and obstruction of a highway and taken into custody.”
Commander Jane Connors, added: “We absolutely recognise the right for people to protest however we will continue to take action against those who choose to break the law, to ensure disruption to Londoners is kept to a minimum.
“We are aware that protestors are expected to target the construction industry this week.
“We are engaging with business across the Capital and would urge anyone who become aware of protests taking place on their premises to contact police at the earliest opportunity.”