If you want to convey that someone should contact the person if they aren't contacted:
* "If you haven't been contacted in this instance, please reach out."
* "If you don't hear from us, please let us know."
If you want to convey that someone should NOT contact the person in this instance:
* "Please refrain from contacting us in this instance."
* "We'll reach out to you if needed. Please don't contact us."
If you want to convey that the person is not available for contact in this instance:
* "I am currently unavailable for contact. Please reach out at a later time."
* "Please do not contact me at this time."
The best rephrasing depends on the specific context and what you are trying to communicate.