Hart has been left on the bench for Manchester City's two games so far this season and Everton are among the clubs being linked with a move for the England shot-stopper.
Regarding that speculation, Toffees boss Koeman said: "What I don't like is talk about rumours, because then we can keep that (going) for two weeks more and there are so many names, players linked to Everton.
"It is today Joe Hart, it will be tomorrow (someone else)
I prefer not to talk about players who are still in contract with other teams than Everton."
But he added: "We always look (at) players to have a stronger squad than we have
If we think we don't have that type of player in the squad, then we will sign that player.
"Really what we need we will bring into the team."
Koeman then emphasised "we need three goalkeepers", before adding: "We have Maarten (Stekelenburg), we have Joel (Robles) and we have a young goalkeeper.
"It is all about a decision we need to make."
Source : PA
Source: PA