United have already signed David De Gea, Ashley Young and Phil Jones this summer and manager Sir Alex Ferguson has admitted they are unlikely to make further signings.
But Gill insists the club are still looking to make another major signing.
“Edwin made it known that last season would be his last so we had planned for a new goalkeeper well in advance. With the others, the opportunities came along and we were comfortable with that,” he told MUTV.
“So we’ve made three signings. We’re looking at one more player to bring in.
“Nothing’s happening – nothing imminent – on that at the moment, but we’ll see what happens when we get home.
“There’ll still be 31 days of the transfer window to see if anything develops. But I’m not working on anything at the moment, in that respect.”
United are looking to bring in a replacement for Paul Scholes, who decided to retire at the end of last season.
Gill added: “We’ve been looking at a particular position and two or three players in that position, but nothing’s imminent at the moment.
“The important point to understand, and Alex has made it clear, is that we need someone who’s going to improve the quality of the squad.
“We’ve got a great squad and to get into that squad you need to be a world-class player. There’s no point, if you can’t get the players you want, in buying someone for the sake of buying someone.
“But you never know – there’s often movement in August. I’m not sitting here saying I’m working on anything specific because I’m not, but that situation could change quickly when we get back to Carrington.”