Chelsea have offered Rooney a route out of Manchester United, but a bid was rejected by the Barclays Premier League champions despite the apparent desire of the striker to leave and there is some way to run in the bid for his services.
Jose Mourinho insisted the England forward is the Blues' only transfer target and, while praising Rooney, experienced goalkeeper Cech preferred to focus on preparing for the new season.
"Wayne Rooney is a great player but at the moment he's a Man United player," Cech said.
"We'll see what's going to happen. He's a great player. Let's see.
"You always want to have the biggest and strongest squad so you can challenge for titles.
"That's why you have a manager and sporting director to take care of that and you have to do the most important part and that's the work on the pitch.
"We already have a few more players and a great squad. If the manager doesn't think we have enough he will try to get players in. It is only his decision.
"For players, we concentrate on getting fit and doing our best, to play as much as we can. That's all we can do.
"In football things are changing every day with every squad. As time goes on, every team can make some changes. Anything can happen."
Mourinho, whose second spell as Blues boss began with a 1-0 win over Singha All-Stars in Bangkok on Wednesday, has already signed Andre Schurrle, Marco van Ginkel and Mark Schwarzer, the latter providing back-up to Cech.
Cech is one of the survivors from the Special One's first spell at Stamford Bridge, when Chelsea won a first Premier League title in 50 years in 2005 before retaining the trophy as the Portuguese established himself as the most successful manager in the club's history.
Cech sees little alteration in Mourinho after nearly six years away.
"He is as hungry as ever, he wants to be successful," Cech said.
"When you have someone who works at such a high standard every day it never changes. It's the same.
"He doesn't do things just for nothing, he always wants to win games, no matter if it is a Premier League game or a pre-season game or Champions League game.
"He's always pushing the players hard to train, to concentrate, to do things in the right way."
Mourinho praised the 'old guard' earlier this week, but Cech recognises there are no favourites in the squad.
"It's the same whether you are 40, 31, 45, 28 or 15," Cech said.
"If you are good enough you play, if you are not good enough you don't play. I think everybody will play on merit, we have to earn our places and we are working to do so."