No it is right. In indian english we mostly use this word to show we are trying our best to achieve it like
I failed my mathematics exam. Next time ! work hard.
I am working hard to achieve my dreams.
If you don't work hard you will fail.
And 'make an effort' means 'प्रयास करो' which means 'to try'.
I was never aware of the following difference before this discussion. "I'll work hard" and "I'll make an effort." could be different in American English, If 'make an effort' is taken literally. So, probably some reenforcement would be added to make the sentences equal: "I'l make a (real/concerted/serious), effort." But the imperative implies that the speaker thinks that the other person is not working hard enough; so, "Make an effort!" is pretty much "Work hard" though "Make an effort." has a somewhat impatient or blaming tone, absent from "Work hard!"