A group of assailants pelted the Iranian Embassy in Berlin with stones and paint and pulled down an Iranian flag, German police announced Thursday.
According to reports, approximately 30 people were involved in the protest.
The assailants, of whom police detained ten, reportedly did not enter the building.
No information has yet been released regarding their possible motives.
German Foreign Minister Guido Westerwelle condemned the "assault" on the embassy, adding that Berlin would do "everything necessary in order to protect the Iranian embassy and all other diplomatic missions", according to a statement.
He also telephoned his Iranian counterpart Ali Akbar Salehi after the incident to express his "great regret", AFP reported.
According to Iranian media reports, Salehi told the German minister that Iran expected the incident to be "seriously pursued" and that those responsible be brought to justice for what he called a "hideous act".
German police gave no details on the nationality or age of those taken in for questioning and was unable to say whether they had been released, according to AFP.