If you change the report into an alert you'll have the ability to send email only if there are results.
Please accept an answer.
run your search -> top right save as dropdown -> an alert -> condition: if count > 0 -> in actions, send results, send email (and everything else you need) -> set cron to the time of day you want the report to run -> save -> enjoy
hope it helps
A little late, but you can go to Settings\Searches, reports, and alerts
Click your report and in the Alert section you can choose the Condition, the one you want is:
If number of events
is greater than: 0