The growing ties between Tehran and Moscow come as Iran has increased its military activity against Israel through attacks by its proxy groups: Hamas, Hezbollah, and the Houthis.
Heusgen told German press agency DPA the Iranian and Russian governments had not been invited because they had not shown a serious interest in negotiations.
The new drone is from the Shahed-101 family of UAVs that all have a distinctive V-shaped tail.
The agreement was finalized during a meeting between the governors of the two countries' central banks in Russia.
Iran plans to acquire more aircraft from Russia in the future.
There is a "clearly a growing relationship in the defense realm" between Iran and Russia, US National Security Council spokesman John Kirby said.
Psalm 83 talks about how Israel’s “enemies growl” and its “foes rear their heads,” with their leaders calling to “destroy them as a nation so that Israel’s name is remembered no more.”
Foreign Minister Sergei Lavrov and Iranian Foreign Minister Hossein Amirabdollahian both spoke in favour of a ceasefire.
The White House said Russia and Iran appeared to be deepening their defense cooperation and that in addition to supplying drones, Tehran was working with Moscow to produce Iranian drones.
Only through concerted efforts can we effectively counter the sponsorship of terrorism and work toward fostering peace and stability in the tumultuous Middle East.