Cahill has impressed greatly since arriving at the Reebok Stadium from Aston Villa in 2008.
His performances at the heart of the Trotters' defence have seen the 25-year-old force his way into the England set-up, and attract interest from several of the Premier League's top sides.
Arsenal, Liverpool and Tottenham Hotspur have all been linked with a swoop for the Sheffield-born stopper, but the Lancashire side's manager has claimed none of them have yet lodged a bid.
"I think it is well known the belief I have in Gary Cahill, the quality he has, but that's the nature of football," Coyle told Sky Sports.
"It only takes a phone call for it to all change but I have said to him he is a Bolton Wanderers player, he is well paid by Bolton Wanderers and he has to make sure he is focused to do the job in hand until something was to change.
"He is such an outstanding player that we are very fortunate to have him.
"I know there is interest from other clubs, nothing concrete in terms of offers, but all these elite clubs know he is an outstanding player so we will have to wait and see what happens with that."
