話さないで

don't speak, don't talk

→ 話す
話さ to speak, to talk + ない Negative + Te-form (conjunctive)
verb · imperative Rare #27,359
don't speak, don't talk
JA: ここでは話さないでください。
EN: Please don't speak here.
Conjugation of 話す

トムのこと話さないでって言ったよね

I told you not to talk about Tom, didn't I?

誰にも話さないで

Don't tell anyone.

そんなに速く話さないで下さい

Please don't speak so fast.

このについてはトム話さないで

Don't tell Tom about this.

来週の計画をトム話さないで

Don't tell Tom about next week's plans.

話さないでください

Please don't talk right now.

— REC / レック (2007)