Finnish shipping company Finnlines Oyj last week turned over banned spare tank parts to Helsinki authorities. The shipment originated from St. Petersburg, Russia.
Lavrov said from Brussels that Russian arms exporter Rosoboronexport wasn't involved in the shipments.
"There was no governmental cargo on the ship and so we're trying to make inquiries into this report," he was quoted by Russia's state-run news agency RIA Novosti as saying.
The Russian company said its relationship with the Syrian military was in line with existing contracts. Finnish authorities didn't reveal the origin country involved in the arms shipment.
The European Union rejected a push this week to amend an arms embargo in Syria in order to facilitate aid to anti-government forces.
"The (European) Council agreed to renew the restrictive measures against Syria for a further three months, amending them so as to provide greater non-lethal support and technical assistance for the protection of civilians," a Monday statement read.
Russia is one of Syria's top weapons suppliers. Moscow, which holds a permanent seat on the U.N. Security Council, has objected to draft resolutions on Syria, saying they lack balance.
An estimated 70,000 people have died in the Syrian civil war.