Azerbaijan's Turan news agency says the protesters are demanding that their wages be increased by 15 to 20 percent.
Local workers complain their salaries are lower than those of employees hired by the company from abroad.
The company today said it was trying to address the workers' concerns. But it neither confirmed nor denied that a strike was under way.
Turan says workers employed by two of McDermott International's subcontractors are also on strike. This information could not be immediately confirmed either.
McDermott International is installing underwater pipelines in the Azerbaijani sector of the Caspian Sea through one of its subsidiaries.