He also confirmed that the £120m fee attached to Nottingham Forest midfielder Elliot Anderson falls outside the parameters the club is willing to meet.
Berrada spoke on United's Inside Carrington podcast after the club agreed a £35m deal with Atalanta for Brazil midfielder Éderson — confirmed as the first signing of manager Michael Carrick's era.
"We have to be really disciplined. We have a plan, we know what we can invest and we need to stick to it. It's very important you don't let the market or the agents dictate what we should be doing."
He framed the club's approach as a direct evolution of last summer's strategy, which delivered Matheus Cunha from Wolverhampton Wanderers, Bryan Mbeumo from Brentford, Benjamin Šeško and goalkeeper Senne Lammens. All four contributed positively to a campaign that ended with United finishing third in the Premier League and qualifying for the Champions League for the first time in three years.
"The template for what we did last summer will be replicated. You never know how you will come out of a window. You have to be really prepared, you have to have a clear plan, you have to know what positions you want to strengthen and you also have to be prepared for any eventuality. We have to be agile and flexible."
On the blend of signings, Berrada was specific.
"We want a mix of experience and youth. A mix of players who have demonstrated they can perform in the Premier League and players that are doing very well outside the Premier League. Whatever decisions we take will not just be for the short term but the long term."
Manchester United are still pursuing additional midfielders and hold strong interest in West Ham United's Mateus Fernandes, valued by the relegated club at £80m. A striker to support Šeško and a left-sided option — potentially a full-back given that Patrick Dorgu is considered more of an attacking player — are also on the agenda.
Director of football Jason Wilcox, director of recruitment Christopher Vivell and director of negotiations Matt Hargreaves will all be central to executing the plan, alongside Berrada and Carrick.