Rav Ovadia asserts that even non-Jews are forbidden to conduct bullfights. However, one may ask that a specific prohibition to conduct bullfights does not appear on the list of the Seven Noachide Laws that the Torah obligates all mankind to abide by.
Rav Yehuda Amital (in a lecture at Yeshivat Har Etzion) answers that we see that the Torah expects and demands every human being to behave decently. Moreover, the Torah demands every human being to refrain from engaging in immoral activities, even if an activity is not formally prohibited by the Noachide code. Failure to do so will result in divine retribution.