I was in a university of california campus, and i was caught with marijuana less than 28g, while also being under 21, will i be fined the state citation or a federal citation?
While the "Feds" don't like marijuana possession or use, state law governs.
However, since you are a UC student, you may also face disciplinary action by the university for violation any the Rules of Conduct that you may have agreed to as a condition of acceptance of your enrollment.
You should consult with and perhaps retain an attorney to represent you in connection with this citation.
it will be state in all likelihood
they should have given you a citation that tells you where to appear