The EU had lifted sanctions because the country had taken steps in the right direction, including releasing political prisoners, Maas said in Berlin.
"We must now discuss in the EU whether this still applies in the light of the past week and the past days," he added, echoing comments from Poland.
Maas' ministry earlier said there were numerous indications of fraud in the election.
Belarus' central election commission said Lukashenko, in power for more than a quarter of a century, won 80% of the vote in Sunday's election, while Svetlana Tikhanouskaya, who emerged from obscurity to become his main rival, took 9.9%.