Iran is Assad's main regional ally, and Tehran has acknowledged sending military advisers to assist his forces in their fight against rebels and jihadist militants.
However it has denied accusations from opposition forces and Saudi Arabia that it has troops on the ground in Syria.
"We invited Hezbollah, but not the Iranians, There are no Iranian troops in Syria and they have not sent any force," Assad told France 2 Television.
Lebanon's Shiite group Hezbollah, which is backed by Iran, has helped Assad make gains against rebels opposing his regime.
In the wide-ranging interview the Syrian leader also denied being behind alleged chemical attacks in northwestern Idlib province last month, and accused the United States of overseeing the creation of the Islamic State group.
"The IS was created in Iraq in 2006 under the supervision of the Americans. The IS came from Iraq to Syria because chaos is contagious," he said, slamming France and other western nations for supporting the jihadists by considering them as the moderate opposition.
"Is it democratic to send weapons to terrorists and to support them? So I have the right to support the terrorists who attacked Charlie Hebdo for example?"
Assad was scathing about efforts of the US-led coalition fighting IS, saying the grouping was "not serious".
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"If you compare the number of air strikes carried out by the coalition composed of 60 states compared to those by our small state you will notice we sometimes strike ten times more than the coalition in one day. Is that serious?
"It took them four months to free what their media calls the town of Kobane on the Turkish border. How can you say this coalition is effective? They are not serious and that is why they are not helping anyone in the region."
He reiterated denials of the use of barrel bombs or chemical attacks, which Syrian forces were most recently accused of using in Idlib province.
"What are barrel bombs?" Assad asked, referring to improvised containers packed with chemicals, shrapnel or other explosives.
"We haven't used chlorine gas and we don't need to," he said, referring to the attacks reported by Human Rights Watch on Idlib.
More than 215,000 people have been killed in Syria since the conflict began with anti-government protests in March 2011 that spiralled into a war after a regime crackdown.
Repeated diplomatic attempts to end the fighting have failed.
Assad said he was open to dialogue if the West "convinces us they are not supporting the terrorists."