The guidelines set strict limits on things like tyre camber and pressures, but also pre-session tyre heating, according to Germany's Auto Motor und Sport.
The report said teams were not allowed to 'boost' temperatures in their respective heating systems beyond 110 degrees for one hour.
But a Force India team member is quoted as saying: "The heating systems are easily manipulated. If you boost more than allowed, you have an advantage."
Auto Motor und Sport said Pirelli has reacted by checking pre-running tyre temperatures not only via the heating systems, but also with their own probes.