“Some of us had to change our pants,” he said on his Twitter feed after he posted a 30-second video of the brief encounter.
The elephant appeared in front of the vehicle and then walked off the road, circled the truck and then charged it from behind, ears flapping, as the vehicle picked up speed and pulled away.
The driver can be heard saying: “I think he’s ok now, he’s going to avoid us”, seconds before the charge.
Schwarzenegger did not identify the reserve where the charge took place.
Game drives and safaris are a major tourist attraction in several African countries, including South Africa, where Schwarzenegger had been for a sports festival at the weekend.
In some parts of the continent, elephants are being relentlessly poached for their ivory to meet Asian demand for the commodity.
Schwarzenegger tweeted: “I’m absolutely in awe of these beautiful animals, and I wish people would stop killing them for their ivory.”