Far-right parties have gained ground across Europe but the rise of the AfD touches a particularly sensitive nerve in Germany because of the country's Nazi past.
Consideration is being given to the question of whether Israel should continue its boycott of the right-wing AfD party in Germany and right-wing AUR party in Romania.
Stephan Kramer's comments come after the Alternative für Deutschland candidate won the local district council election in the same state.
The party opposes economic sanctions against Moscow over the Ukraine war and dispute that human activity is a cause of climate change.
Israeli governments have boycotted the party and refused to hold ties with the AfD traditionally.
The spy agency said that the Young Alternatives wanted a society that was as ethnoculturally homogeneous as possible.