"What is happening now, with the Americans and some others carrying out airstrikes, is ineffective. They have been bombing for six months and there are no signs of the Islamic State's potential weakening," Churkin said during a Moscow-New York video conference arranged by Rossiya Segodnya news agency.
Islamic State is a Sunni terrorist group that has been fighting the Syrian government since 2012. Since 2014, an US-led international coalition has been conducting airstrikes against ISIL positions in the country.
Russia has repeatedly criticized the coalition for not first seeking approval from either the UN Security Council or the Syrian government before launching the campaign and called on the global community to join forces with Damascus in the anti-terror fight.
On Tuesday, Syrian President Bashar Assad said in an interview with Russian media that the US-led international coalition against ISIL had failed since the militant group had been expanding its operations in the country despite the air campaign.