The Syrian premier also said the United States and Arab countries are not serious about finding a political solution to the crisis in the country.
Russia and the United States agreed in Moscow on May 7 to convene the international conference, which will serve as a follow-up to an earlier Geneva meeting held in June 2012.
This came as reports said last week that Saudi Arabia has signed a 50-million-dollar deal with Israeli army to supply the foreign-backed militants with old Israeli military equipment and arms.
The weapons include different kinds of anti-tank missiles, military vehicles, artillery equipment, and night vision devices.
On June 14, US President Barack Obama ordered his administration to provide Takfiri militants in Syria with weapons, which include assault rifles, shoulder-fired rocket-propelled grenades and anti-tank missiles.
Last month, US congressional panels agreed to the White House decision to supply arms to the foreign-sponsored Takfiri groups operating in Syria despite deep skepticism in the Congress over the plan.
Syria has been gripped by deadly unrest since 2011.
According to UN Secretary General Ban Ki-moon, more than 100,000 people have been killed and a total of 7.8 million of others displaced since the outbreak of the violence.