"Large (banks) are not taking part. Small ones are, yes," Novak told reporters, in the first such confirmation by a top Russian official.
"Major banks are not involved as they have taken into consideration the possibility of any sanctions to which they might become subject."
In 2011, the U.S. Congress passed a law requiring buyers of Iranian oil to make significant cuts to their oil purchases, or risk being cut off from the U.S. financial system.
The European Union followed suit by imposing sanctions last July against Iran's oil and shipping industries which barred Europe-based insurers from covering tankers that carry Iranian oil. Later, it also added bans on financial transactions and on sales to Iran of shipping equipment, among other measures.
Novak, who spoke after meeting Iranian Foreign Ali Akbar Salehi in Moscow, declined to name either the banks involved or the scale and nature of their possible financing of oil exports from Iran.
Salehi, in Moscow on a trade mission, said that Russian companies would be welcome to participate in developing the growing oil industry of the OPEC member state.
The West suspects of Iran of seeking to acquire atomic weapons, while Tehran insists its nuclear program is peaceful. Six-power talks with Iranian nuclear negotiators are due to be held in Almaty, Kazakhstan, on February 26.
(Reporting by Vladimir Soldatkin; Editing by Douglas Busvine and William Hardy)