Croft, 31, has suffered a serious knee injury in August and never made much of an impact on the Bluebirds' first team.
The former Blackburn player revealed he can still train with the club a short-term deal still a possibility if he can prove his fitness.
Said Croft: "I knew they weren't going to offer me a full year, but I did get told by the management they were going to try and offer me a month-to-month deal.
"But when it came to it, the gaffer told me he was unable to persuade the people upstairs to give me that.
"What was on offer was the... opportunity to train with
"But it's very vague and there's nothing in writing to say this is what is going to happen, so it's end-of-contract time really but with that opportunity.
"It's a time for reflection now and moving on and perhaps looking at other things."
The majority of players set to leave
Kirk Huggins, Richard Ingram, Arran Lee-Barrett, Michael Parkins, Danny Thomas, Craig Attard, Sean Cronin, Michael Hartley and Jamie Rewbury.