"We are serious in talks and we want the talks to be based on the law so it will bear practical results. We hope that other sides are serious too," Ahmadinejad told Assad in remarks broadcast live on state-run television.
On Saturday evening Ahmadinejad was quoted as telling his Syrian counterpart that Tehran "will not give an inch on its nuclear rights."
His comments coincide with this weekend's US deadline for Iran to respond to an international package of incentives for it to freeze its drive to enrich uranium amid warnings of new sanctions if it does not.
After meeting Iran's negotiator Saeed Jalili on July 19 in Geneva, EU foreign policy chief Javier Solana asked for a response in two weeks, but "if it's in 16 days instead of 14 it's not a problem. We are not obsessed with a date," an EU diplomat said earlier on condition of anonymity.
The Syrian leader's visit follows a trip to Paris a month ago during which French President Nicolas Sarkozy urged Syria to "persuade Iran" to prove that it is not seeking nuclear weapons.
"When we were in France we told them about the Syrian position on Iran's nuclear issue but they asked us if we have details of the Iranian programme," Assad said on Sunday in Arabic through a translator.
"In this trip we got details, so in future if we are asked again we know Iran's position."
Iran has so far been slapped by three sets of United Nations Security Council resolutions demanding that it halt uranium enrichment.
This process to produce fuel for nuclear power plants can also be used to make the fissile core of an atomic bomb.
The West fears Iran's atomic programme is a cover for making nuclear weapons, a charge vehemently denied by Tehran which says it needs nuclear power to produce electricity for a growing population.
