From a philological perspective, it's not a command, since the verb is not imperative:
Δόξαν παρὰ ἀνθρώπων οὐ λαμβάνω
λαμβάνω is 1st person singular Present Indicative Active.
In the Present Active Indicative, the kind of action is linear, the relationship of the subject to the verb is active, i.e. the subject is performing the action rather than being acted upon, and the degree of contingency is zero.
If it were a command, the verb form would have been λαμβάνε
EDIT: as requested, here is a short description of verbs in OT Greek:
In Greek, tense indicates not only time of action, but more especially kind of action. The German word "Aktionsart," meaning "kind of action," is often used with reference to what is indicated by the tense of a verb. There are three basic kinds of action:
- linear. It is also called durative, continuous, or progressive. It can be represented graphically by a line. In this case, the speaker conceives of the action as happening. The Present tense indicates this kind of action.
- punctiliar and can be represented by a point. In this case, the speaker conceives of the action without any notion of its continuance. This kind of action is associated with the Future tense. Note carefully that the future tense does not imply the action takes place instantaneously. Rather we should say the speaker conceives of the fact of the action without indicating continuity.
- ongoing result of previous action, and can be represented graphically by a line proceeding from a point. In this case the speaker conceives of the action as being the ongoing result of a previous event.
Then there is mood. Think of different moods (also called "modes" in some grammars) as different degrees of contingency. Indicative Mood which contemplates the action with no contingency at all. The action is indicated. It is real, or at least the speaker presents it to be considered as real. Even if the statement is false, it is at least presented as if it is a fact.