The 18-year-old Canadian gifted his beloved pet Pac to a young girl at the Jingle Ball in Atlanta, Georgia last week.
The 'Boyfriend' hitmaker told the fan to "take care" of the hamster, which he adopted in October, and she promised Pac would be going to a good home.
However, officials at the California Hamster Association insist Bieber was cruel to give away his pet, reported TMZ online.
"(Hamsters) often succumb quickly to illness and death (when faced with) sudden environmental change... The moment that hamster was handed off to a screaming girl in a harsh, frenzied environment was likely the moment it gazed at the short path to its doom," said a spokesperson for the group.
Bieber has also come under fire from politicians in the Philippines after he mocked Filipino boxing legend Manny Pacquiao online after his recent defeat.
