Tel Aviv District Judge Gideon Ginat told the OCI to remove the mascot, named "Shpitzik," from all its publications and Internet sites, Haaretz reported.
Ginat found the mascot bore numerous similarities to "Kishkashta," the Educational TV puppet character.
Educational TV sued the OCI, claiming copyright infringement, and the judge ruled the Olympic character was "far more than a 'humanization of a cactus.'"
"It seems that the resemblance might be misleading ... In both cases the size of the head is disproportional, and that's true of his hands as well. The ears are designed in a similar way, as are the thorns."
Even the shade of green was "almost identical."
"At the end of the day," Ginat wrote, "it seems to me that the defendant seized a well-known character, added several marginal elements and gave it a new name, for its own needs."
He ordered the OCI to pay Educational TV $13,402 to cover legal costs.
The Olympic character was chosen online by Web surfers from among five the OCI posted.
The judge denied damages, saying the mascot had not been used.
Eldad Koblenz, Educational TV's director, told Haaretz, "We will continue to safeguard our cultural property."