UNITED NATIONS — Syria, facing mounting global pressure over its decisions to move tanks into cities against its own citizens and to shoot unarmed demonstrators, tried to defend its record against blunt denunciations from the United States and others on Tuesday at the United Nations, where the Security Council is struggling to forge a collective response.

Ambassador Bashar Jaafari, the Syrian envoy, repeated the government’s claim that the unrest at home was the work of as yet unidentified foreign agitators trying to undermine Syria’s stability and that armed infiltrators were responsible for the shooting of protesters.

“This unrest and riots in some of their aspects have hidden agendas,” Mr. Jaafari told reporters. “Some armed groups take advantage of the demonstrations; they get within the demonstrators and start shooting on the military men and the security forces. This is why there are many casualties.”

Mr. Jaafari also defended President Bashar Assad’s record, saying that more political reforms were coming on the heels of Mr. Assad’s decision to lift the emergency law.