The Syrian government "wants to put an end to the bloodshed," Damascus's UN envoy Bashar al-Jaafari told reporters in Geneva.
But he lashed out at the opposition High Negotiations Committee (HNC), which made a late showing in Geneva for scheduled UN-brokered peace talks but has said, for now, it will not negotiate.
The indirect talks on ending Syria's nearly five-year conflict had been scheduled to start on January 25, but were postponed until the 29th when Jaafari and his delegation sat down with the UN's Syria envoy, Staffan de Mistura.
But HNC, the main opposition umbrella group, spent days debating whether to travel to Geneva, before finally arriving in the Swiss city late on Saturday, only to announce it would not be engaging in talks.
Before agreeing to sit down for the so-called proximity talks, in which de Mistura is to shuttle between the sides, HNC has demanded that humanitarian aid first gets through to besieged towns, that the bombing of civilians ceases and that hundreds of prisoners are released.
Jaafari said the government firmly rejected any "conditions" imposed by the opposition delegation, saying it would be a "violation" of de Mistura's invitation to talks.
"The conference did not start on time because the opposition delegation is late. This is a sign that they are not serious," Jaafari said.
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President Bashar al-Assad's government wanted "to stop the suffering of the Syrian people," he said.
"We are ready to work to find a solution."
Opposition 'not credible'
The problem, he said, was that the opposition delegation was "not credible."
He said the full list of opposition delegates remained unclear, hinting some might even be "terrorists".
"We don't know who is taking part in the talks, neither does de Mistura," he said, insisting: "We are not holding talks with terrorists. This is exactly why the special envoy insisted on holding indirect talks."
Syria's government uses the word "terrorist" to describe a host of armed opposition groups, including the Army of Islam rebel faction which is a member of HNC.
Since the conflict began in March 2011, more than 260,000 people have been killed and half of the country's population have fled their homes, with millions exiled to neighbouring countries and beyond.