The Dons turned down an undisclosed bid for the 29-year-old, who has made 22 appearances this season, on Friday.
"It's one of those things. You put a value on a player and that's what happens," Warnock told BBC Radio Wales Sport.
"We are just weighing up two or three other players at the moment to see what we're going to do."
He continued: "We try to keep away from the last-minute deadline but I'm afraid it's always there. There's a possibility that we might make another offer."
Aberdeen manager Derek McInnes says he has told Cardiff to "be serious" with regard to the fee if they wish to pursue their interest in Hayes.
Meanwhile, Warnock revealed he was in talks to bring a Premier League goalkeeper to the Cardiff City Stadium, and said he would not have sanctioned former keeper David Marshall's move to Hull City last summer.
"If I had been here all season I would have desperately gone out of my way to make sure he didn't leave," he added.
"We lost two goalkeepers on the last day [of the transfer window] and didn't recruit anybody, which has really snookered me really.
"I've been looking to get a permanent goalkeeper in now, I've made two offers for players which have both been turned town and now I'm trying to get somebody on loan from the Premier League."
Cardiff City boss Neil Warnock says the club may make another offer for Aberdeen winger Jonny Hayes.