"Do not do it, please."
Translation:Nie rób tego, proszę.
I'd guess that's true even more often, but that's only a guess.
BTW: the one idea I got for a situation when it won't work: pomylić się (to err, to make a mistake), although 'mylić się' would be the imperfective.
Pomyl się! (Make a mistake! - what you think to yourself for example when you're playing chess and you hope the opponent makes a wrong move)
Nie pomyl się! (Do not make a mistake!)
It would be a good way to say it in a polite way (not exactly 'formal' but appropriate for formal situations), but there are two things to fix in your answer: it's "robić" with an i, and secondly, one grammatical error.
So the verb "robić" takes a direct object in Accusative, which for "to" is also "to". But it's negated here, and negated Accusative turns into Genitive (no other case changes when negated), which for "to" is "tego". The right way is "Proszę tego nie robić".