No, that's plainly wrong.
Marx and Engels used the phrase several times, both in private correspondence, letters to editors and in their later published work.
In the Critique of the Gotha Programme, Marx wrote:Between capitalist and communist society there lies the period of the revolutionary transformation of the one into the other. Corresponding to this is also a political transition period in which the state can be nothing but the revolutionary dictatorship of the proletariat.
Engels wrote in the Civil War in France:
Of late, the Social-Democratic philistine has once more been filled with wholesome terror at the words: Dictatorship of the Proletariat. Well and good, gentlemen, do you want to know what this dictatorship looks like? Look at the Paris Commune. That was the Dictatorship of the Proletariat.
In a private letter by Marx:Now as for myself, I do not claim to have discovered either the existence of classes in modern society or the struggle between them. Long before me, bourgeois historians had described the historical development of this struggle between the classes, as had bourgeois economists their economic anatomy. My own contribution was 1. to show that the existence of classes is merely bound up with certain historical phases in the development of production; 2. that the class struggle necessarily leads to the dictatorship of the proletariat; 3. that this dictatorship itself constitutes no more than a transition to the abolition of all classes and to a classless society.
The phrase captures the essence of what Marx and Engels were advocating as a political objective: the complete control of society by the working class.