Kristin Rose-Moehring suggested in an internal circular of the Ministry of Family Affairs that stanzas containing the word "fatherland" (Vaterland) should be replaced by "homeland" (Heimat).
"Brotherly with heart and hand" should be replaced with "courageously with heart and hand," she wrote, noting that Austria had tweaked its national anthem for gender balance.
In 2012, Austria substituted "sons" with "daughters and sons" in parts of its national anthem.
Canada too announced plans last month to make its anthem more gender neutral, changing the words "all thy sons" to "all of us".
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Julia Kloeckner of Merkel's CDU party also opposed the suggestion, saying: "I would have thought that other things were more important for women than changing the national anthem."
And the general secretary of the CDU, Annegret Kramp-Karrenbauer, likewise said she saw no need for change.
"I am an emancipated woman and I never felt excluded by this anthem," she said.
The far-right Alternative for Germany also hit out on Twitter, saying: "We will not yield our fatherland!"
The party also recently called for German to be inscribed in the constitution as the country's official language.
Sung to a melody composed by Joseph Haydn, the lyrics of the Song of Germany were written by August Heinrich Hoffmann in 1841.
Reunified Germany in 1991 adopted only the third stanza as its anthem.
The first stanza, which includes the line "Germany above everything", was used as Nazi propaganda.