Daeubler-Gmelin said a formal challenge would be mounted in coming months.
The German Government decided at a meeting on Wednesday to demand the withdrawal of the patent because of an error which failed to make clear that the approval did not apply to human tissue.
Justice Minister Herta Daeubler-Gmelin told the country's parliament after the meeting: "The Patent Office's decision was legally and ethically wrong."
Daeubler-Gmelin said a formal challenge would be mounted in coming months.
The Munich-based European Patent Office has admitted a mistake was made when it granted the patent for human cell research leading to possible replacement of diseased human tissue, such as that found in people suffering from Parkinson's disease.
Rainer Osterwalder, a spokesman for the office said: "We made a mistake. This should not have been granted in the present form."
Misinterpret agreement
Greenpeace, which discovered the error, said the omission could be misinterpreted and used to support genetic cloning.
The patent refers to "a method of preparing a transgenic animal" but the Patent Office said the term "non-human" should have been included because "animal" can also mean human in English scientific usage.
The patent technically violates EU guidelines that take effect on 31 July banning "processes that would change the genetic identity of human organisms".
Mr Osterwalder said his office was investigating how the mistake got through, but that inattention and a high volume of applications were the likely cause.
German and Italian politicians have promised to file a challenge - the only remedy available after the Patent Office said it could not unilaterally undo the error.
Italy's EU policy minister, Patrizia Toia, said the Italian government may likewise take legal action to intervene against what she called a "disastrous decision".
Italian Environment Minister Edo Ronchi asked for reforms at the European Patent Office, revision of an international directive on patenting biotechnology and a moratorium on patents from the office.
"If we have to discover from a complaint from Greenpeace that errors were committed, who can give us guarantees on the more than 2,000 other biotechnological patents released in a few months by the office?" Ronchi asked.
A spokeswoman at Edinburgh University said: "The patent does not relate in any sense to the cloning of human beings
"It covers research with human cells in the laboratory, which is accepted scientific research."