The man, identified only as Yamen A., was held at dawn by Special Forces in the northeastern town of Schwerin, the federal prosecutor’s office said in a statement. Several apartments were also searched in the region, which is north of Berlin, AFP reported.
The man is suspected of having "planned and already concretely prepared an ... attack in Germany using very powerful explosives," the statement said.
"It has not yet been established whether the suspect already had a target in mind or not," it said, adding that prosecutors did not have any information whether the suspect belonged to "a terrorist organization."
The Syrian had made a decision "no later than July 2017 to explode a bomb in Germany with the aim of killing and wounded as many people as possible."
In the following weeks, he began to acquire the chemical products and materials necessary to build a bomb.
German police have been on high alert to the threat of attacks, particularly after a truck rampage claimed by Daesh (also known as ISIL or ISIS) killed 12 people in Berlin last December.
A report published in September found that Berlin authorities had missed several opportunities to arrest and deport the driver, Tunisian asylum-seeker Anis Amri.
Officials admitted a series of security failures that allowed Amri to register under multiple identities and evade authorities while he was in contact with militants.