The Organization for Security and Co-operation in Europe (OSCE) is a good forum to discuss the growing tensions between Russia and the vast majority of other European countries.
Everyone involved sits there on an equal footing at the table.
Russia also needs to hear at the OSCE from the representatives of those countries that Foreign Minister Sergei Lavrov recently condescendingly described as “territories” that were “orphaned” after the collapse of the Soviet Union. The OSCE is also a good place to recall post-Cold War commitments that Moscow itself made but failed to fulfill within that organization.
There is a lot about this in the OSCE documents: starting with the general principles such as respect for human rights, inviolability of borders and the sovereignty of others, to which all member states profess in theory, to concrete agreements such as the withdrawal of all Russian troops from the from Moldova's breakaway Transnistria, which was supposed to be completed in 2002 but hasn't even started yet.
With its observer mission, the organization could also have a stabilizing role in the conflict area in eastern Ukraine - if the fighters supported by Russia did not regularly obstruct it.