President Viktor Yushchenko had put forward an idea to summon representatives of parties that made it into parliament in the March 26 elections but Communist leader Petro Symonenko was the only one to attend.
He left after waiting for his colleagues for 30 minutes and said the no-show signaled their lack of respect.
"Let them speak about their future participation in negotiations now," he said.
The opposition Party of Regions, led by President Yushchenko's former rival in the 2004 presidential race Viktor Yanukovych, said it was against today's meeting.
The pro-Russia party blocked the rostrum in parliament for a few days last week after the "orange" trio of the pro-presidential Our Ukraine bloc, the Yulia Tymoshenko Bloc and the Socialists had formed a coalition and agreed on nominees for the posts of prime minister and parliamentary speaker.
But parliamentary faction member Taras Chernovol said Monday that Yanukovych's presence at the roundtable would have been premature.
"We think that expert groups must first get together and draft a document, and only then should party and bloc leaders join the process," he said.
Chernovol also dismissed statements of Mykola Tomenko from the Yulia Tymoshenko Bloc that political forces represented in parliament had coordinated a document at the weekend.
"There is no document whatsoever," Chernovol said.
He said that the Party of Regions did not understand the very idea of a roundtable because the Supreme Rada's conciliatory council and parliament itself were enough for negotiations, but added that the leading opposition party remained ready for further negotiations in any format.