Wuqi is right. By law the Police can't even disclose that they warned you. You are legally right to say or state that you have not commited any offence. You are no different to anyone else who have not even been to a Police station at all.
Your parents are smart by saying you are on probation to keep you on the straight and narrow. Nowdays we have parents who will blame the Police and let the kids run wild.
Wish you the very best.
what about joining the police force as a civilian post. Will that be a problem.