"No time has been set, and the factors are not yet in place if we want (a US-Russian peace initiative dubbed Geneva 2) to succeed," Assad told Al-Mayadeen.
"Which forces are taking part? What relation do these forces have with the Syrian people? Do these forces represent the Syrian people, or do they represent the states that invented them?" the embattled leader asked.
The United States and Russia have been trying to organise the Geneva 2 conference -- first announced last year -- on the heels of a deal which Syria accepted to destroy its chemical arsenal by mid-2014.
Assad has systematically refused to recognise as legitimate the National Coalition opposition umbrella group, which insists on his ouster, a demand the regime rejects.
"How can these forces represent the Syrian people if they live abroad. They don't dare to come to Syria... But claim to control 70 percent of Syrian territory," through fighting on the ground, he said.
"There are many questions about the conference... What is the framework of the conference?" Assad asked.
He has also repeatedly accused the Coalition of working under the orders of regional and Western backers.
"The solution (to Syria's war) must be a Syrian solution, regardless of whether foreign powers recognise it. It doesn't matter. What matters is that the Syrian people recognises it," said Assad.
'Why not run for re-election?'
"The issue is a Syrian issue... Whether the conference is held or not is not what matters most. The most important issue is, should the conference be held, will it succeed or not? That is the question. And up until now, the factors are not yet in place for it to succeed."
Asked whether he would run for re-election, Assad, who succeeded his later father in 2000, said: "My answer depends on two factors. The first is the personal desire, and the second is the will of the people.
"Regarding the first point, the one related to me personally, I don't see any reason why I shouldn't run in the next election."
Kerry, in Paris where he met Arab League representatives ahead of a meeting on Tuesday of the opposition and its Western and Arab backers, warned Assad's re-election would doom the country.
"If he thinks he's going to solve problems by running for re-election, I can say to him, I think that certainly this war will not end as long as that's the case that he's there," Kerry said.
Assad's interview also came as UN-Arab League envoy Lakhdar Brahimi was in Baghdad on the second leg of a regional tour to raise support for the peace conference, which according to the chief of the Arab League should be held on November 23.
The Syrian leader said he would welcome Brahimi back to Damascus as long as "he sticks to his mandate and does not overstep it."
"He is tasked with a mediation mission. A mediator should be neutral," said Assad.
Brahimi has not visited Damascus since late 2012 when he came under harsh criticism from Syrian authorities for urging Assad not to run for re-election.
In the interview Assad also described Syria's branch of the Muslim Brotherhood, a key bloc of the opposition, as a "terror group", the blanket term used by his regime to refer to opponents and rebels that have risen against him since March 2011.
"The years since I came to this position up until the start of the Syrian crisis have proven at several junctures that it is an opportunist group that relies on hypocrisy, not religion," he said.
And he charged that oil powerhouse Saudi Arabia, a main backer of the Syrian opposition, was carrying out US policy against his regime.
"Does anyone dare to objectively describe (Saudi policy on Syria) as the policy of an independent state? Saudi Arabia is a state that fully implements the policies of the United States," said Assad.
Damascus has consistently refused to recognise the existence of a legitimate revolt calling for political change, frequently describing the uprising against Assad's rule as a foreign plot against Syria.