Football's world governance Fifa same a picture of the trophy would breach "intellectual property" rights.
The 29-year-old championship leader hoped to wear the helmet for his home Grand Prix at Hockenheim this weekend.
"I would have preferred to hold the trophy as a tribute to the fellows however I respect the legal state of affairs," he said.
Rosberg could prefer to keep different references, like the ensign and 4 stars to represent four World Cup wins.
In a statement, Fifa same it absolutely was "obliged to require action against any unauthorised copy of its property during a business context".
Rosberg showed his support for Federal Republic of Germany on his Facebook page
It added: "We cannot permit a businessly branded helmet to feature the trophy as this may threaten the rights of our commercial affiliates.
"We appreciate Nico Rosberg's want to congratulate the German team and have so been in discussions with the Rosberg team to try to seek out an answer, whereby he's still able to show his support for Federal Republic of Germany while not exploitation Fifa property during a business context."
Germany won the 2014 Fifa World Cup with a 1-0 ending over Argentina in extra-time on Sunday. The previous European nation won the planet Cup 3 times - in 1954, 1974 and 1990.
Rosberg, UN agency leads his British team-mate Lewis Hamilton by four points, had with pride shown off the new helmet style on Tuesday.
"This are going to be my Hockenheim World Cup special edition helmet with the Fifa trophy. however does one find it irresistible @DFB_Team," he tweeted in relevancy the national aspect.