One of Trump's border officials told Politico that the administration is planning to permanently bar Canadians who invest in or start legal cannabis businesses in the US or Canada from entering the USA.
A nationwide legalisation of cannabis goes into effect in Canada next month.
There have been concerns within Canada's growing cannabis industry for months that they may face trouble crossing the border.
In July, a Vancouver businessman was banned from entering the US for life because he had investments in US marijuana companies.
Immigration lawyers have said they have heard similar stories from clients in the industry.