EU envoys are set to discuss the new package next week for final approval before the summer break.
The Commission will also amend existing sanctions to make sure they do not hit Russia's food and grain exports, the three officials said.
African countries have said EU sanctions contributed to the ongoing food crisis, chiefly caused by the war in Ukraine and the Russian blockade of Ukrainian ports from where cereals are usually exported to the world.
The EU has long denied that its sanctions affected food trade. Proposed tweaks are meant to make sure that rules are not misinterpreted by traders, including a ban on access of Russian ships to EU ports, one official said.
Under that measure, Russian ships are already allowed to enter EU ports if they carry food or medicines.
But some traders have avoided food exported from Russian ports that are indirectly owned by Russian state-owned companies that have been sanctioned by Brussels. The new package will clarify that these ports are exempted from sanctions, the source said.
The Commission is also expected to tighten the existing ban on Russian vessels entering EU ports to prevent them from bypassing sanctions by offloading their cargoes at outer docks, the source said. For that purpose, the definition of ports is to be extended.
The new measures are considered "a maintenance and alignment package," one of the officials said, referring to it as a "sixth-and-a-half" set of sanctions for its limited scope compared with previous rounds that hit Russian oil or coal.
However, some measures could have a serious impact on the affected sectors.
One source said imports of Russian gold through third countries would also be affected, but did not elaborate on how it would work.
Brussels will also tighten existing measures, with new curbs on the imports of goods that could be used for military purposes, including chemicals and machinery, the source said.
New individuals and entities considered close to the Kremlin will also be added to the EU blacklist that requires freezing of their assets and travel bans, according to the two sources and one other EU official.