Representatives of Syria's government and opposition High Negotiations Committee (HNC) are in Switzerland for the sixth round of UN-backed peace negotiations, but there has been no sign of progress.
He said negotiations to end the six-year conflict needed to take place "without any rest, without any break".
In other developments, the USA -led coalition against Daesh (ISIS) said it did not conduct strikes in the eastern Syrian town of Albu Kamal this week that reportedly killed dozens of civilians.
"The coalition commander assessed the threat and after shows of force didn't stop the regime forces and those forces refused to move out of the deconfliction zone, the commander on the ground called for the air strike as a matter of force protection", a senior United States defense official told Fox News.
Last month, the USA fired cruise missiles on a government air base after accusing Assad's military of killing scores of civilians with a sarin-like nerve agent.
The opposition has continued to demand that Syrian President Bashar al-Assad step down as part of a political transition process, which the government sees as a non- starter.
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Images on social media showed the vehicle with a smoking hood slightly overturned on a barrier at a sidewalk in Times Square. Vehicle plows into crowd in Times SquareThe official spoke on condition of anonymity because the investigation was ongoing.
The reports gave different death tolls for the IS attack on the village of Aqarab al-Safiyeh in central Syria.
The militants stormed homes in the southern part of Aqareb al-Safi village before government forces pushed them back into the desert, the state news agency SANA reported. The dead included more than two dozen women and children, some of whom were beheaded, as well as Syrian troops, according to state media, medical officials and an opposition monitoring group.
He added that the constitution was "the exclusive right of the Syrian people, and we do not accept any foreign interference in it". Most of the residents belong to the Ismaili branch of Shiite Islam.
"United Nations mediator Staffan de Mistura's office declared the development as a first tangible step to the intra-Syrian talks".
The Islamic State group has launched an offensive against government forces in central Syria near the highway that links the capital Damascus to the northern city of Aleppo.
Razzouk said 120 people were wounded; SANA said 40 were wounded.