The militants opened fire on the vehicle in the Pasni area of Gwadar, officials said.
In the firing, two security guards on top of the vehicle were killed, he said.
The oil exploration company officials were in Pasni to conduct a survey of the area when the incident happened.
The Gwadar port became operational last week when Prime Minister Nawaz Sharif launched the first ships to take chinese trade goods to Sri Lanka, UAE and EU countries.
Attacks on government, security officials and workers of private oil and gas companies in parts of Baluchistan is common in the province which is facing a separatist movement from insurgents and also other sectarian and terrorist violence.