Their Malaysian backers want to invest heavily in the club, build a new training ground and increase their stadium capacity, but, according to the Cardiff City Supporters Trust, it comes on condition they implement the changes.
"We were told in no uncertain terms that this was a fait accompli," trust chairman Tim Hartley told BBC Wales.
"This investment is going to come into the club. We were shown a design of the logo, Cardiff City will be playing in red, they will be wearing a dragon on their chests."
Vice-chair Tracey Marsh said: "I feel like they've got us over a barrel and we are not going to take this lying down."
Championship Cardiff have played in blue for more than 100 years but red is considered a lucky colour in parts of Asia, while the dragon appears on the Welsh national flag and is hugely symbolic in Asia.
The fates have not been kind to Cardiff this season after they were beaten by Liverpool on penalties in the final of the League Cup at Wembley in February and lost to West Ham United in the play-offs.
"We would like to assure supporters that any decisions will include the long term interests of our supporters, our community and the survival and development of Cardiff City Football Club in a highly competitive and modern sporting industry," the club said in a statement.
"As a club we also appreciate the importance of our history, along with our position within the community."