The cameraman was arrested in the Al Khadhra quarter, western Baghdad where he was filming the aftermath of a bomb explosion outside a police station on Monday.
AFP cameras captured Hamza being searched and then handcuffed whilst pushed up against a military jeep.
This is not the first time that Aljazeera journalists have been targeted by the American military in Baghdad.
Earlier this month, Aljazeera correspondent Atwar Bahjat was arrested while covering a bomb attack in the Al Ghazzaliya district of the capital.
She was held in a US military holding area at Baghdad airport overnight, before being released.
In April , Aljazeera journalist Tariq Ayyoub was killed in Baghdad after an American missile hit the Al Jazeera offices in the city.
The American occupation forces denied targeting the Aljazeera office, despite being given the co-ordinates for the television channel’s Baghdad bureau by the channels managers.
Hamza was held in Iraq for two days, but no explanation was given as to why the cameraman was arrested.
He arrived at the scene of the explosion, half an hour after the bomb exploded outside a police station in Al Khadhra.
A US soldier searches Hamza
Aljazeera spokesperson Jihad Ballout said that Aljazeera was relieved to hear that Hamza had been released, but many questions still remained unanswered.
”We don’t understand why our cameraman was arrested, we were told by the Americans that they were suspicious of him, but he was only doing his job.
“We will do whatever it takes to ensure that our staff can continue to work in all parts of the world and will be pressing the Americans for answers.
“As far as I am aware Samir Hamza and Aljazeera haven’t been issued with an apology,” said Ballout.