He was seen on the roof of the business just before 01:00 on Thursday 1 August, but he gave up his attempted burglary when the alarm sounded.
Guernsey Police say he then ran up the hill the cafe is at the foot of.
Now, officers are investigating the incident, treating it as an attempted burglary. They ask anyone who has any information, or who saw someone running from the area around that time, to contact PC 26 Willmor on 725111 or to report what they know anonymously through Crimestoppers on 0800 555 111.
Pictured top: The entrance to the Terrace Thai Garden Cafe.