Russia has signalled that it will not sign new weapons contracts with Syria until the situation there calms down.
The country will continue with previously agreed exports, but will not be selling new arms to Syria, Vyacheslav Dzirkaln, deputy chief of the Russian military and technical co-operation agency, told Russian news agencies.
The Russians have blocked the UN's Security Council from taking strong, punitive action against the Assad regime and are seen as the country's key arms supplier, putting it in conflict with the West.
Syrian activists say that about 14,000 people have been killed in an uprising in the country since March 2011.
Russia has been providing Syria's army with spare parts and assistance in repairs of the weapons supplied earlier, Mr Dzirkaln said. He insisted that Russia does not sell helicopters or fighter planes to Syria.
Foreign Secretary William Hague said he welcomed the decision but added that Britain "would like to see a halt of all deliveries of weaponry to a regime that has embarked on the killing of so many of its own people".
US secretary of state Hillary Clinton last month issued a harsh reprimand to Russia, saying that Moscow "dramatically" escalated the crisis in Syria by sending attack helicopters there. The state department acknowledged later that the helicopters were actually refurbished ones already owned by the Syrian regime.
Russian president Vladimir Putin earlier said that Russia is still committed to a peace plan by UN envoy Kofi Annan, saying that the Syrian government and opposition groups should be "forced" to start a dialogue.
Mr Annan's six-point peace plan was to begin with a ceasefire in mid-April between government forces and rebels seeking to topple Mr Assad, to be followed by political dialogue. But the truce never took hold, and almost 300 UN observers sent to monitor the ceasefire are now confined to their hotels because of the escalating violence.
Mr Hague called on Russia to show "a strong commitment to secure the implementation and mandate the implementation of what Kofi Annan has put forward".