After a strong end to the season, the Latics narrowly missed out on this weekend's Sky Bet Championship play-off final after succumbing to a 2-1 semi-final defeat to QPR.
Despite having their second-tier status confirmed for another season, Rosler insists they won't have to sell their best players.
"The good thing - and my chairman has been very strong about this - is that we don't need to sell any players," he told the Wigan Evening Post.
"I had several meetings last week with my chairman - very positive meetings and I was very happy with what he had to say with regards going forward.
"Never once did he intimate to me the need to sell anyone - quite the opposite. He wants us to be even more competitive in certain areas.
"Clearly every player at every football club has his price, but our players are under contract.
"I don't think certain clubs would be able to afford them - unless we got the kind of offer we got for James McCarthy, which obviously any club would have to consider."
Rosler believes the club will provide funds for recruitment this summer, which will help boost their quest to achieve promotion next season.
"We will be very competitive next year. We will be investing in our playing and coaching staff, and I think it's important to keep working on changing the culture at the football club," he said.
"The players have been fantastic since I have been here, and there's nothing more pleasing for a manager to see than for his players to be putting in overtime effort for you.
"The QPR tie showed what we are all about. We never gave up, and the least we deserved was a penalty shoot-out. I think the players can hold their heads high in the knowledge that from December they gave me everything they had.
"We have already come a long way, but there is still a long way to go."