A directive sentence is a sentence that can express a directive speech act, but not a statement or question.
Alternatively, this could be called "imperative sentence".
imperative–hortative (INF/CXN) = a speech act which requests that the action expressed in the propositional content of the imperative–hortative be carried out, prototypically by the addressee but possibly by other persons; and the construction that expresses this speech act. Example: Dance! is an example of the English imperative–hortative construction for the second person, and Let’s dance! is an example of the same for the first person plural. The term ‘hortative’ is sometimes used for a first person imperative–hortative, and ‘jussive’ for a third person imperative–hortative. A negative imperative–hortative is a prohibitive. (Sections 12.1, 12.4)