The men appearing in the video were identified by German broadcasters as Rene Braeunlich and Thomas Nitzschke on Sunday.
Looking distraught and exhausted, Braeunlich and Nitzschke, both engineers from Leipzig, were shown in front of a black banner with white Arabic writing on it.
One of the men, thought to be Nitzschke, could be heard saying in German: "We have been here for more than 60 days. We are at the end of our nerves. Please help us. We cannot bear this any longer. Please help us."
Braeunlich and Nitzschke were abducted on January 24 outside their workplace in the industrial town of Baiji, 180km north of Baghdad.
The German government stopped short of identifying them, but confirmed it had received a video showing the hostages.
Angela Merkel, the German chancellor, said her government would exhaust all options.
"I can assure you that we will do everything possible within our power to save the life of the hostages and to get the hostages back and free to Germany," she said, adding that the video was being examined.
A statement by their captors posted on a website often used by armed Iraqi groups demanded the release of all prisoners held by US-led forces in Iraq and said the two would be killed if its call was ignored.
"Learn that if our demands - the release of all men and women held at the prisons of the occupation and stoppage of all assistance to the Americans and their allies - are not met, the just sentence would be urgently carried out," Ansar al-Tawhid wa-Sunna said.
"We have been here for more than 60 days. We are at the end of our nerves. Please help us. We cannot bear this any longer. Please help us"
"This is the final call for the two German agents," it said in a message to the German government and the families of the hostages.
In February, the group issued what it called a final ultimatum saying it would kill the captives unless Berlin met its demands that Germany end co-operation with Baghdad, close its embassy and force all German firms to leave the country.
The video aired on Sunday has a March 28 date stamp on it and is believed to be the fourth video message showing the Germans.
Aljazeera also aired a brief portion of the tape.