McCann had made an offer to the goalkeeper, keen to keep him at the Keepmoat for a sixth season.
But the terms on offer did not match those expected by Marosi and he leaves the summer on the expiration of his contract.
“We offered Marko a contract and he refused it,” McCann said.
“I shook his hand on Tuesday and wished him good luck because we can’t get anywhere near his demands.”
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Marosi confirmed his departure with a message on Twitter, writing: “I would like to say thank you to @drfc_official, to all the staff, the lads and all the fans who stuck by me all these years I have been here.
“We have had some great times together.
“I’ve met some amazing people and made great friends but it’s time for me to move on and to take on a new challenge.
“I will miss you all and I wish you all the best for the future.”
Marosi was handed the gloves at the start of the season by Grant McCann but lost his place to Ian Lawlor in November.
He would receive it back however when Lawlor suffered a season-ending injury in January.
The former Slovakia U21 international joined Rovers in August 2014 from Wigan Athletic, whom he had impressed while playing for Burnley College where he was studying.
He made his debut in September 2014, replacing injured loanee Jed Steer in a 3-0 defeat to Walsall.
Marosi was often used as back-up until the 2016/17 season in League Two where he was selected as Darren Ferguson’s number one until an injury in January forced him out of action with Rovers moving to bring in Ian Lawlor.
Barring a spell late in the 2017/18 season Lawlor was the favoured choice.
Marosi departs Rovers having made 95 appearances, during which time he conceded 118 goals and kept 24 clean sheets.