The vehicles struck the boulders almost simultaneously at 1.35am yesterday at West Calder in West Lothian.
The articulated lorry burst two tyres while the car suffered engine damage.
Both drivers were unharmed in the incident.
Officers believe the boulders were placed across the whole roadway at a point some four miles west of the junction with the B7008 Harburn Road.
A police spokesman said: “This utterly dangerous and reckless act led to damage to two vehicles and those responsible must be brought to justice.
“While, thankfully, no one was hurt, these actions could have led to serious injury and police are keen to trace those responsible as a matter of urgency.”