You can also defend yourself legally!
The legal situation is complicated but it is generally questionable if EU-citizens may be excluded from German welfare benefits. In the last few weeks the responsible social court in Berlin has already given welfare benefits to people who were denied Hartz IV before – for the time being provisionally.
Find a social helpdesk or a lawyer for social law (Sozialrecht) to protest at the Jobcenter and apply for preliminary legal protection („einstweiliger Rechtsschutz“) at the social court. Do this quickly! You will receive benefits from the date of your application.
To sue the Jobcenter does not cost any money! The costs for the lawyer will also be coverred!