Both Muallem and Salehi questioned Western support for rebel groups, saying such fighters were the cause of bloodshed in Syria.
Salehi said Iran believes dialogue is needed to bring an end to the violence. The Syrian government is ready to talk, he said.
Their remarks come two days after the United States promised to send food and medical supplies -- but not weapons -- to rebels in the first such move since the conflict began nearly two years ago.
At the same time, European nations began to explore how to strengthen rebel fighters short of arming them after a European Council decision allowing aid for civilian protection.
U.S. Secretary of State John Kerry, speaking after meeting opposition leaders at a Friends of Syria conference in Rome, said the aid would help fighters in their effort to topple al-Assad.
He did not say how much aid, but did announce that the United States would separately give $60 million to local groups working with the opposition Syrian National Council to provide political administration and basic services in rebel-controlled areas of Syria.
That's on top of $50 million in similar aid the United States has previously pledged to the council, as well as $385 million in humanitarian assistance, Kerry said.
The European Council carved out an exception in its sanctions against Syria on Thursday to allow for the transfer of nonlethal equipment and technical assistance for civilian protection only. It did not specify what kind of equipment could be involved.
Meanwhile, violent clashes have been taking place in al-Raqa province, near Syria's northern border with Turkey, according to the Syrian Observatory for Human Rights, a UK-based opposition group.