Rouhani met Monday with German Ambassador to Tehran Michael Freiherr von Ungern-Sternberg in Tehran.
Germany is a party to multilateral negotiations between Iran and the five permanent members of the U.N. Security Council. Rouhani said his government hoped Germany would play a "positive and constructive role" in next week's talk in Geneva.
Catherine Ashton, the foreign policy chief for the European Union, said Geneva would host this year's third round of nuclear negotiations with Iran.
Two previous rounds of talks in Kazakhstan, held before Rouhani took office in August, were described as amicable but ineffectual.
Rouhani said his administration wouldn't pursue a nuclear weapons program. Yukiya Amano, director general of the International Atomic Energy Agency, said last month it's essential for Iran to cooperate with inspectors because of the "possible military dimensions to Iran's nuclear program."
Iran maintains the right to peaceful nuclear research as a signatory to the Nuclear Non-Proliferation Treaty. U.S. President Barack Obama has said he'd respect that right so long as he had assurances from Iran it wouldn't weaponize the program.