"Today it is Russia's readiness in principle to work on the sanctions which is important," the senior diplomatic source told reporters, speaking on condition of anonymity.
But "going into detail on this would be somewhat premature," the source added.
Medvedev was scheduled to arrive Monday in France, where he is expected to discuss the standoff over Iran's nuclear programme with his French counterpart, Nicolas Sarkozy.
Russia and France are working closely together on devising plans that would ensure Iran had access to nuclear fuel while encouraging Tehran to renounce uranium enrichment, French diplomats say.
As a permanent, veto-wielding member of the UN Security Council, Russia would need to give its support in order for the Council to impose a new round of sanctions on Iran.
Western powers led by Washington have been pushing the UN Security Council to impose a new round of sanctions against the Islamic Republic in a bid to rein in its disputed nuclear programme.
The United States and its Western allies believe Iran is seeking to build an atomic bomb under the guise of its civilian nuclear programme, though Tehran insists the programme is peaceful in nature.
Russia, which had enjoyed close ties with Tehran for many years, has shown growing irritation with Iran in recent months and has said it could not exclude a new round of UN sanctions against Iran over the nuclear issue.
