He stressed that the new sanctions package will concern Russian energy carriers.
"The most critical, undoubtedly, are the future sanctions packages," Tsahkna emphasized.
"The 20th sanctions package has been adopted, the 21st is being prepared, and it will be quite tough, especially regarding energy carriers."
The EU Council adopted the 20th sanctions package against Russia, which includes 120 new individuals and entities, on April 23.
This is the largest sanctions package in the past two years, providing for economic restrictions on key sectors that support Russia's war against Ukraine.
In particular, the package contains the basis for a future ban on maritime shipments of Russian crude oil and petroleum products. The application of these bans will still be discussed with G7 countries.
China's Commerce Ministry declared a "resolute protest" over the inclusion of Chinese companies in the EU's 20th sanctions package against Russia on April 25.
The sanctions package includes Chinese companies accused of supplying dual-use goods or weapons systems to the Russian military-industrial complex.