If Iran waste all their missiles and drones on futile attempts against the iron dome, there will be less for Russia to attack civilians in Ukraine where it is much harder to protect a larger area. This also means that Iran can no longer hide by claiming not to be directly involved in a conflics.
Germany condemns Iranian attacks
Germany condemns Iran's attack "in the strongest possible terms" and warns Tehran it is risking all-out regional war, a spokesman for Chancellor Olaf Scholz says."With this irresponsible and unjustifiable attack, Iran is risking a regional conflagration. Germany stands closely by Israel's side," the spokesman said.