Ilan Mizrahi, the outgoing head of Israel's National Security Council, a government advisory body, told a RIA Novosti correspondent in Delhi that the arms deals are a result of worsening relations between Moscow and the United States.
The official's comments come one week after Israeli Prime Minister Ehud Olmert's visit to Moscow, when he urged President Vladimir Putin not to sell weapons to Iran and Syria.
"Supplies of the most up-to-date weapons to Iran and Syria do not contribute to stability in the region," Mizrahi said.
Military-technical cooperation with the two countries raises concerns "in view of statements by Syria of their readiness to repossess territories through military force, and by Iran, which openly calls for the annihilation of the state of Israel," he said.
Mizrahi said the Middle East conflict had become a confrontation between radicals and pragmatists, and that the international community was trying to support the pragmatists.
"I do not think that cooperation with the armies of Iran and Syria, who represent the radical forces, is helping stability," he said.
Mizrahi, a former deputy head of Israeli secret service Mossad, announced his resignation as Security Council chairman in September, over the prime minister's continued sidelining of the group of experts. He will continue to chair the council until November.