More than 20 cherry trees, forming part of a newly planted avenue in Heath Park were vandalised this weekend.
The trees were gifted to the park as part of The Sakura Cherry Tree Project which was created to celebrate 150 years of friendship between Wales and Japan.
Cabinet Member for Culture, Parks and Events, Cllr Jennifer Burke-Davies: "These trees were only planted in January and were meant to symbolise friendship and understanding so for them to be subject to such mindless destruction is sickening. It's a deliberate act of vandalism, a crime, and I fully condemn this completely unacceptable behaviour.
"Our parks team are in the process of assessing the full extent of the damage and will be reporting the incident to the police. I would urge anybody who has any information related to this incident to contact Crimestoppers on 0800 555 111."
The process of sourcing replacement trees has already begun, with the cost of replanting estimated to be in the region of £4,000.
Despite this, and other recent incidents, such as the vandalism of Bute Park in autumn last year, Cardiff remains one of the UK's safest cities, with the second lowest overall crime rate of the English and Welsh core cities.
The council works with partners through the Community Safety Partnership to ensure the city's publicly accessible green space remains safe and potential measures to deter crime and anti-social behaviour, such as improved lighting, are currently being considered.