And he is adamant only those with the potential to achieve success will be recruited under his Blues reign.
Pompey’s head coach has so far signed eight players this summer.
However, substantial work is still required following a massive post-season overhaul of his squad.
Cowley along with brother Nicky, head of recruitment Phil Boardman and Roberto Gagliardi have been overseeing an exhaustive player hunt.
And the Blues boss is prepared to wait for developments in the market rather than rushing in filling his squad with stop-gap signings.
He told The News: ‘We just have to make some decisions – but must remember that we’re Portsmouth Football Club.
‘I could have a full squad now, but I am not willing to compromise.
‘I know what this club needs to be successful and the players that I could sign today won’t take this club to where we want us to go.
‘Being patient has to be the strategy, the money we have available financially is where we are at.
‘You have to be fair to the owners, we have just come through 18 months of a pandemic. Through the back of it they have spent £10m on the stadium, they have bought Roko, which is huge for the sustainability of this football club moving forward.
‘We have a competitive budget, but a lot of it is taken up and, as a consequence, we have a small amount to work with. I’ve got to try to use that as intelligently as I can.
‘There are players already contracted with the club, so what we must do is try to work through this. We have to attempt to create the best squad we can.’
The Blues have so far bought Liam Vincent from Bromley and taken Gavin Bazunu and Gassan Ahadme on loan.
There have also been the free transfer arrivals of Clark Robertson, Shaun Williams, Ryan Tunnicliffe, Kieron Freeman and Jayden Reid.
Pompey’s first-team squad has lost 12 players since the end of last season.
Among them were many regulars of a side which finished a disappointing eighth in League One.
Cowley added: ‘I could sign players today, but they won’t take Pompey to where we all want it to go, so the strategy has to be to use the depth in the window – and it is a long window.
‘We know that when windows go into the actual season, as this one does, the moment league games start happening there will be some high emotion, maybe some rash decisions.
‘We are working 20 hours a day at the moment, but we love football, it's no issue.’
A message from the Editor, Mark Waldron
The News has launched a subscription offer which gives you unlimited access to all of our Pompey coverage, starting at less than 14p a day.
You can subscribe here to get the latest news from Fratton Park - and to support our local team of expert Pompey writers.