Trump brought back the punishing sanctions after unilaterally pulling out of a landmark 2015 deal between Tehran and Western powers to halt Iran's nuclear ambitions.
"We still think that it is a mistake to give up on the nuclear accord with Iran," Maas said in an interview with the daily Passauer Neue Presse. "We are fighting for the deal because it also serves our purpose by bringing about security and transparency in the region."
Noting Iran's geographic proximity to Europe, Maas warned that "anyone who's hoping for regime change must not forget that whatever follows could bring us much bigger problems."
"Isolating Iran could boost radical and fundamentalist forces," he said, adding that "chaos in Iran, as we have experienced in Iraq or Libya, would further destabilize an already troubled region."
In a desperate bid to save the nuclear accord, European governments have pledged to do what they can to keep business links with Tehran.
Despite the political will to hold firm, many large European firms, such as German automaker Daimler, are leaving Iran for fear of US penalties.
The US Ambassador to Germany, Richard Grenell, said he is pleased to see German businesses stopping their trade with Iran.
"[It] is helping pressure Iran back to the table," he tweeted.
Newspaper headline: Germany warns US’ sanctions are destabilizing