The bank's experts however rated the risks of the international loan programme as "exceptionally high" and the Greek government's performance as "barely satisfactory", the magazine said.
The paper's authors also voiced "considerable doubt" about the Greek government's ability to implement essential reforms, said Der Spiegel.
The paper, reportedly written for Germany's finance ministry and the International Monetary Fund (IMF), also criticised the latest credit tranche, saying it had been approved due to "political constraints".
The Bundesbank had denied to Der Spiegel that this was a reference to Germany's campaign period before September 22 elections and a desire by Chancellor Angela Merkel's government to talk up progress in Greece.
International lenders would have to agree another loan package after the German election and by early 2014 at the latest, the central bank's paper reportedly said.
Last month German Finance Minister Wolfgang Schaeuble said in Athens that new financial aid for Greece could be considered late next year if Athens hauls its budget out of the red.
The indebted country, in its sixth year of recession, has been forced to cut jobs, pay and pensions in order to secure 240 billion euros ($314 billion) in rescue funds from the European Union and IMF.