"We are fervently searching for the abductors with a view to securing the release of the Germans," Rivers state police spokeswoman Rita Abbey told AFP.
"The Germans were taken across the sea. But we hope to track down their captors very soon," she assured.
Abbey said a soldier was shot and wounded when unknown gunmen seized the two workers of construction firm Julius Berger in Port Harcourt on Friday. She could not confirm a report in the local press that the man had died.
“We are acting on the assumption that two German citizens have been kidnapped in Nigeria,” a spokesman of the German Foreign Office told news agency DDP in Berlin on Saturday.
The ministry's crisis division is working intensively for the release of the two men, the spokesman said.
No group has claimed responsibility for the incident, the latest to rock oil-rich Nigeria in recent months.
The Niger delta, home to the country's multi-billion-dollar oil and gas resources, has seen numerous kidnappings targeting foreign energy firms in the past two years.
The attacks are often claimed by some militants who demand a greater share of oil wealth for the region's inhabitants, while others carry out kidnappings for ransom or political reasons.
A Julius Berger employee abducted in March in Nigeria was released after several hours.
A senior Nigerian official of Julius Berger said the construction firm was "monitoring the situation" in the Niger delta following the kidnapping, but refused to say whether the incident could prompt it to pull out of the region.
Julius Berger, the Nigerian arm of German Bilfinger Berger, began operating in the country in 1965. Nigerian investors own 50.04 percent of the company while foreigners own 49.96 percent.
Several foreign firms, including French tyre company Michelin and oil servicing firm Wilbros, have left the Niger delta because of security problems.
The unrest has reduced Nigeria's oil output by a quarter, causing Nigeria to lose its position as Africa's biggest oil producer to Angola, according to April figures from the Organization of Petroleum Exporting Countries (OPEC).