He urged allies to act outside of the U.N. Security Council, as resolutions there can be vetoed.
"The rebels now are fighting with primitive types of weapons against the killing machine. We need weapons that will allow us to stop tanks and planes," Sieda said.
Meanwhile, Syria's foreign minister decried what he called a "vicious" international plot against the Syrian regime.
"I can tell you that we are facing a global war against Syria, and as a proud Syrian I can tell you that it is a great honor to be part of a great country that is facing a ferocious attack by certain countries," he told reporters in Tehran after a meeting with his Iranian counterpart. Moallem also described a "media campaign" by the United States and others about chemical weapons in Syria.
Iran's foreign minister accused Israel of being behind "a conspiracy against Syria."
"It is completely ridiculous and delusive to believe that there is a possibility of creating a vacuum in the leadership in Syria," Iranian Foreign Minister Ali Akbar Salehi said. "We call upon the people of the region to be fully aware and not to move in the wrong direction, because there will be severe consequences that will go beyond the borders of the region to the outside world."
The Syrian crisis started in March 2011, after al-Assad's regime cracked down on peaceful protests.
More than 20,000 people, mostly civilians, have died in the conflict, the LCC said. Last week, U.N. Secretary-General Ban Ki-moon said almost 17,000 people have died.