In an address to the Arab League in Cairo, Lavrov said that any ships carrying weapons would be "detrimental to the continued conflict."
Russia's February 24 invasion of Ukraine disrupted shipments and sped up a rise in global commodity prices.
Since the start of the war, a blockade of Ukrainian ports by Russia's Black Sea fleet has trapped tens of millions of tonnes of grain, worsening global supply chain bottlenecks.
Egypt is one of the world's top wheat importers and last year bought about 80% of those imports from Russia and Ukraine.
In its response to the war, Egypt has been torn between long-standing ties with Russia and its close relationship to Western powers that have sanctioned and sought to isolate Moscow.
Russia, Ukraine, Turkey and the United Nations signed a deal on Friday (July 22) to restart Ukrainian wheat exports by sea, but a Russian strike on Odesa on Saturday (July 23) put implementation of the agreement in doubt.
Lavrov earlier met with Egyptian foreign minister Sameh Shoukry and offered reassurances over Russian grain supplies to Egypt.
Western embassies had lobbied Egypt and the Arab League ahead of Lavrov's visit, which included talks with President Abdel Fattah al-Sisi and representatives of the Arab League.