Employees walk towards the entrance of the Google China headquarters in Beijing.
Lawmakers in Berlin will debate the bill in the Bundestag (lower house) on Thursday. Google says the law would make it harder for users to retrieve information via the Internet.
Google launched its campaign against the bill on Tuesday with advertisements in German newspapers and a web information site called "Defend your web".
"Such a law would hit every Internet user in Germany," Stefan Tweraser, country manager for Google Germany, said in a statement. "An ancillary copyright means less information for consumers and higher costs for companies."
The campaign has caused outrage among some members of German Chancellor Angela Merkel's center-right coalition.
"The campaign initiated by Google is cheap propaganda," said conservative lawmakers Guenter Krings and Ansgar Heveling.
"Under the guise of a supposed project for the freedom of the Internet, an attempt is being made to coopt its users for its own lobbying," the two said in a statement.
Supporters of the law argue that newspaper publishers should be able to benefit from advertising revenues earned by search engines using their content.
Under the plans, publishers would get a bigger say over how their articles are used on the Internet and could charge search engines for showing articles or extracts.
German Justice Minister Sabine Leutheusser-Schnarrenberger, a member of the Free Democrats (FDP) who share power in Merkel's government, said she was astonished that Google was trying to monopolize opinion-making. She is responsible for the law.
"Panic mongering"
Germany's newspaper industry, suffering from economic slowdown and keen to get its hands on any revenues it can, backs the plans and railed against Google's campaign.
"The panic mongering from Google has no justification," Germany's BDZV newspaper association said in a statement.
"The argument from search engine companies that Internet searching and retrieval will be made more difficult is not serious. Private use, reading, following links and quoting will be possible, just as before."
Internet lobbyists in Brussels fear the European Commission is sympathetic to publisher demands for a piece of Google's profits online. Recent statements, they say, are proof.
"Consumers are not the only ones facing difficulties," Michel Barnier, the EU's internal market commissioner, said in a speech on November 7. "Think of newspaper publishers who see the content they produce being used by others to attract consumers on the net and generate advertising revenues."
French newspapers and magazines want Google to pay them for linking to their articles on Google. The French government has named a mediator to negotiate with the press and Google to try to get a deal by the end of the year.
If no deal emerges, President Francois Hollande's government will ask parliament to draft a law modifying copyright laws to protect the press from appropriation of its content online, according to a letter signed by two ministers on November 28.