Germany is one of those western nations involved in a long-running dispute with Tehran over its nuclear programme, but it has also been one of the biggest exporters to Iran.
Last week, the government of Chancellor Angela Merkel urged the German Near and Middle East Association NUMOV in a letter to cancel two conferences on Iran, Handelsblatt said.
"These events clearly contradict the government's policies and could cause bigger foreign policy damage to Germany," the daily quoted the letter by the economy ministry as saying.
"For this reason, I would like to ask you not to go ahead with these events in the name of the economy ministry and the chancellor's office," the letter said.
The two conferences, an information event on Iran for German companies in western Duesseldorf, and a meeting by German company representatives with Iran's Oil Minister Gholamhossein Nozari in Berlin, went ahead nevertheless, the paper said.
Recent figures show Berlin has significantly cut the value of new credit guarantees it offers firms that do business with Iran, but German exports to the country still rose last year.
German firms receive the guarantees for exporting goods to markets considered risky and the figures suggested firms are prepared to take the risk of doing business with Iran even without the safety net of export guarantees.
Iran's Nozari called on German firms to invest in Iran.
"Iran can become a safe and reliable energy supplier for Germany," he told Handelsblatt in an interview. "We offer giant opportunities and the early bird catches the worm."
Nozari said Iran was intensifying plans on a so-called "Persian pipeline", which would transport gas from Iran to Europe. His country, which has the world's second-largest gas reserves, was also ready to cooperate on the Nabucco pipeline project to bring gas to Europe from central Asia.
Germany, whose consumption of about 100 billion cubic metres of gas a year represents a fifth of the total in the European Union, is among six major powers seeking to convince Iran to suspend nuclear work the West fears is aimed at making bombs.
Tehran says its nuclear programme is aimed at generating electricity but its refusal to halt uranium enrichment has drawn three rounds of U.N. sanctions since 2006, as well as separate U.S.-led financial and other measures. (Reporting by Kerstin Gehmlich; Editing by Matthew Jones)
