"We didn't tell her that I was coming," = "On ne lui a pas dit que je venais,"

Could someone clarify why imperfect is used in the above example? I thought it would be future (je viendra). The linked lesson is "Expressing continuing action with the imperfect tense in French" but this does not seem like a continuing action? And the rest of the sentence is in future tense as well. 

Thanks in advance!