Crimea seceded from Ukraine in 2014, and after holding a referendum, joined Russia. The West condemned the move as an illegal annexation and imposed sanctions on Moscow.
The $3.6 billion bridge across the Kerch strait, part of which was unveiled by Russian President Vladimir Putin in May, has drawn strong rebukes from the EU which says it is a further violation of Ukraine's sovereignty.
The six companies cited in Tuesday's statement from the Council of the European Union include construction firms PJSC Mostotrest and CJSC VAD.
The firms will have their assets frozen in the EU, and EU persons and entities will not be able to make funds available to them, the European Council said.
"Through their actions they supported the consolidation of Russia's control over the illegally annexed Crimean peninsula, which in turn further undermines the territorial integrity, sovereignty and independence of Ukraine," the European Council said.
Ukraine's foreign minister Pavlo Klimkin has welcomed the additional EU sanctions against Moscow.
