I have accidentally given students assignment guidelines that conflict with the course coordinator's. How I can rectify my mistake? I am a tutor and I have given guidelines to students on how to complete the assignment. After three weeks later I found out that the course coordinator expected different requirements than what I have told students. 

There is a clash now and students are very confused. They are emailing me about who they should follow. Given there is still one week left in the due date of assignment. How I can mend my mistake? I worry anything I will do now go against me. 

I should have consulted with coordinator before deliver the guidelines to students. But I just wanted to help students as they were feeling lost because the course coordinator didn't provide any guidelines whatsoever. Students said the assignment is vague and I just helped them with the structure of it. But now coordinator wants a different structure than what I have given to students four weeks ago.
Talk to the course coordinator immediately and coordinate your next steps. 

Apparently, there was a serious breakdown in communication, and 


  the course coordinator didn't provide any guidelines whatsoever


suggests to me that you are not the only one to blame.

Whatever your next steps will be, they need to be aligned with the coordinator and his expectations. You may be able to extend deadlines, adjust grading rubrics or something else.

Next time, make sure you know what the coordinator wants. (And the coordinator should make sure, too.)