When asked about Lookman at his press conference on Wednesday ahead of Friday's Premier League away clash with Hull, Koeman said: "There is interest for the boy, yes."
The Dutchman was not prepared to estimate when a deal for Lookman, who has scored seven goals so far this season, might be wrapped up.
Everton have also targeted Manchester United duo Morgan Schneiderlin and Memphis Depay and, regarding the forthcoming window more generally, Koeman said: "It is a busy time because we have a lot of games in a short time and, of course, I'm involved in new players, in making the team stronger.
"We are working on that. We have certain interest in some players."
He added with a smile: "Some names (the club are being linked with) are true and some names are not true. That is all speculation.
"One time it is possible, but most of the time it is bulls***!"