Al Hasawi did not reveal who the four players were but claimed that Forest would now try to secure some loan signings over the next few days, with the Championship clubs being allowed to complete temporary deals after the permanent deadline.
"I would like to take this opportunity to inform our supporters that we today attempted to sign four players in a bid to further bolster our squad," Al Hasawi revealed in a statement on the club's website.
"Regrettably, the value of each player rose over the course of the day to a point where we no longer considered any of our targets as suitable signings at this time.
"We will now turn our attention to the loan market before having another major push in the January transfer window."
Forest are currently fourth in the Championship table.