Brereton, whose first goal for Forest was a late winner against Aston Villa last Saturday, has been linked with a move away from the City Ground.
Forest have sold a number of academy graduates in recent years including Oliver Burke, who joined RB Leipzig last August for £13m.
Nottingham Forest have no plans to sell Man United and Liverpool target Ben Brereton
But Al Hasawi has now played down speculation linking young striker Brereton with an exit.
Al Hasawi told the Nottingham Evening Post: "Why would we want to sell him?
"We have similar players coming through the academy.
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"We have invested money in the academy and Gary has done an amazing job, which is why we have good players coming through now.
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"We have given Gary [Brazil] everything he has asked for and we now have some good players coming through as a result.
"We have very good players coming through, in fact and that is very positive for the future of the club. We want them to play here."