Completely depends on the context, you'd use the same sentence in different contexts in English, so why not here? If a guy tried to tell your kids that it's safe to walk off some cliff, because there's an invisible bridge that will stop them from falling, this would be an appropriate thing to say (and likely followed by some much stronger words).
The best way to say this in North American English is: Whatever you do, don't believe him. The expression is always used with a negative command. Duo gave a strange English expression: Absolutely do not ..... (It is a VERY WEIRD English sentence.) The correct English expression, in my opinion, is Whatever you do, don`t (verb). This is my two cents.