Chelsea are reported to be lining up an approach this month for Cahill but Coyle believes it the January transfer window is not in the best of interests for him.
Bolton set Cahill's price tag high at £20 million
Owen Coyle, the Bolton Wanderers manager, believes a January transfer would not be in Gary Cahill's best interests - and insists it will require a bid of at least £20million (Dh113.57m) if the defender is going to move on from the Reebok Stadium.
Chelsea are reported to be lining up an approach this month for Cahill, whose performances for Bolton over the past few years have earned him a growing list of admirers.
Coyle accepts the fact that the 25-year-old England international could soon leave the club, but thinks now would be the wrong moment. And when the time does come, the Scot knows the kind of price Bolton would be looking for.
"I don't fear bids for Gary or any other player because they have been playing so well," Coyle said.
"Could it happen? Absolutely, because they are top players.
"But if it is Gary that we are speaking about, when those sort of players move for £20m, £25m or £30m - because that is what it would take - they are better suited to moving in the summer.
"Then they can get a pre-season under their belt with the group and obviously it would be an elite club, to pay that sort of money.
"I feel if that type of player signs for someone in January, they are under pressure to hit the ground running straightaway and I don't think they are given enough time to settle in to whatever fantastic football club they would go to."
Coyle stressed he has yet to receive contact from any other clubs about Cahill.
"I think there was speculation regarding Gary Cahill yesterday. I can sit here now very comfortably and say I have had no dialogue with any other football club regarding Gary or any of my other players," Coyle said. "Long may that continue, because I think it is important that the group we have got, we keep them together and we try and add one or two fresh faces to help what we have."
Coyle has ruled himself out of the race to land David Beckham, although he did speak of his admiration for Carlos Vela, Arsenal's young Mexican striker. Coyle signed Jack Wilshere, the Gunners midfielder, on loan last January and has been linked with a similar move for Vela, 21, who he described as an "outstanding" player.
"It's fair to say I would like to help the group that we have," Coyle said.
"We had only 15 players at the weekend at Liverpool, so we'd like to get one or two in to help the team. Time will tell who becomes available and who wants to come.
"Carlos Vela is an outstanding player. I think what happened was that Arsene Wenger [the Arsenal manager] said he might consider letting him go out on loan and then people have looked and put two and two together.
"Bolton have a very good relationship with Arsenal, obviously with Jack Wilshere last year. Hopefully we played a small part in his continuing development. " Meanwhile, Coyle confirmed that defender Andy O'Brien's proposed move to Leeds United is still to be finalised. "It has certainly not happened yet, but Andy was given permission to speak to Leeds, as he was with Cardiff and Ipswich," Coyle said. "There is nothing signed and sealed, but there is every chance that will come to fruition in the next couple of days."