In Spanish, the imperative mood is not used only for strict orders. Very often, it is a simple request, piece of advice, instruction, or warning. If the sentence is negative, no is placed before the verb.
For example:
No hables.
Don’t speak.
No corras.
Don’t run.
No abras la puerta.
Don’t open the door.
No lleguéis tarde.
Don’t be late.
At first glance, it may seem that it is enough to put no before a regular command. But in Spanish, it does not work that way. The negative form of the imperative is not formed like the affirmative one. After no, you use a form that matches presente de subjuntivo.
Let’s compare:
Habla más despacio.
Speak more slowly.
No hables tan rápido.
Don’t speak so fast.
Come la sopa.
Eat the soup.
No comas tanto azúcar.
Don’t eat so much sugar.
Abre el libro.
Open the book.
No abras el libro todavía.
Don’t open the book yet.
This is where students often make mistakes. They memorize the affirmative forms habla, come, abre, and then try to say no habla, no come, no abre. For addressing someone as “tú,” that would be incorrect. You need to say: no hables, no comas, no abras.
Imperativo negativo can sound soft when it is advice:
No te preocupes.
Don’t worry.
No tengas miedo.
Don’t be afraid.
No pienses demasiado.
Don’t think too much.
It is also used in requests:
No me llames tan tarde.
Don’t call me so late.
No cierres la ventana, por favor.
Don’t close the window, please.
No me esperes.
Don’t wait for me.
In stricter situations, it becomes a prohibition or instruction:
No fumes aquí.
Don’t smoke here.
No uses el móvil durante el examen.
Don’t use your phone during the exam.
No toques eso.
Don’t touch that.
On signs and in general rules, the infinitive is often used:
No pasar.
Do not enter.
No tocar.
Do not touch.
No aparcar.
No parking.
But if we are speaking to a specific person, it is better to use a personal verb form:
No pases por aquí.
Don’t pass through here.
No toque esto.
Don’t touch this.
No aparquen aquí.
Don’t park here.
Pronouns also need special attention. In the negative imperative, pronouns are placed before the verb. This is an important difference from the affirmative form.
Correct:
No me digas eso.
Don’t tell me that.
No te levantes todavía.
Don’t get up yet.
No lo compres.
Don’t buy it.
No se preocupe.
Don’t worry.
In the affirmative form, the pronoun is attached to the verb:
Dímelo.
Tell me that.
But in the negative form, it stands separately:
No me lo digas.
Don’t tell me that.
If there are two pronouns, both are placed before the verb:
No se lo digas.
Don’t tell him / her that.
No me lo compres.
Don’t buy it for me.
No nos lo expliquéis otra vez.
Don’t explain it to us again.