Sam Ellis has confirmed Sheffield United will not be pursuing deals for Shaleum Logan, Gregory Vignal or Kerrea Gilbert.
The trio all linked up with The Blades last week and featured in Saturday's 2-0 friendly win over neighbours Rotherham United.
Although United are keen to bolster their backline before the start of the new campaign, none of the players will be staying on.
Assistant manager Ellis insists the South Yorkshire club remain in the hunt for the right additions before the season starts.
"We know we need extra cover in case of injury and suspensions and that is what we are aiming for," Ellis told the club's official website.
"We won't be signing Vignal, Gilbert or Logan and the search goes on.
"We are endeavouring to find the right additions and there will be more to look at next week.
"There are no definite names to announce right now but there will be on Monday because they will feature at Notts County on Tuesday night."