Are aggressive ideas because of depression or psychosis?

Aggression: Possible in mood disorders with or without psychosis.

Yes: The probability of violent behavior in higher for patients with schizophrenia/psychotic disorders than patients with mood disorder including depression, whose risk is higher than in those without any mental disorder. Patients with a mental disorder and comorbid substance abuse have the highest probability, in one study 12.6 times higher for males and 9.1 times higher for females.

Possibly: Aggressive ideas can be symptoms of mental illness, but certainly do not by themselves refect a mental disorder. Aggressive ideas is a broad term which may encompass normal reactions or feelings, to symptoms of mood disorders or psychosis, or can be symptoms of personality disorders, or can occur in ptsd. Even might be OCD when there are aggressive unwanted ego dystonic thoughts one cannot stop.