No. Zakat is validated by the intention in your heart, not by announcing it — "Actions are but by intentions" — and Allah praises giving charity discreetly to the poor. Many poor people are humiliated by being labelled zakat recipients, so it is perfectly valid to hand it over as a gift or assistance while intending zakat. What you may not do is disguise it as payment for work, use it to settle an obligation you already owe (such as maintenance of your wife or children), or give it without first satisfying yourself that the person genuinely falls into one of the eight categories — which sometimes requires a discreet question or a trusted intermediary.
Evidence — the daleel
On deen2u
Informational, not a personal fatwa. Consult a qualified scholar for rulings on your situation.