In the report, think tank British Future said the June 24 referendum outcome was a "vote of no-confidence" in existing policies, the BBC reported on Thursday.
It said public expectations of curbs on low-skilled migration must be met.
The think tank has also released a survey suggesting almost half of Britons do not believe the government will reach its net migration targets.
Ministers have pledged to reduce net migration to below 100,000 by 2020.
British Future's report is published ahead of the release on Thursday of the latest net migration figures, the BBC reported.
Net migration -- the difference between the estimated number of people settling in the UK and those emigrating -- rose to 333,000 in 2015, the second-highest figure on record, and has been above 300,000 for the past five quarters.
British Future's survey of 2,400 people says 44 per cent of those polled said the target was unlikely to be met in the next five years -- even after Britain withdraws from the European Union.
But 37 per cent still thought the target was likely to be achieved.
