But he stressed that for a halt to the violence, the rebels and their backers would need to be involved too.
"In order to succeed in any initiative, it takes two sides," Maqdisi said in answer to a question from AFP.
"The Syrian side is interested in exploring this option and we are looking forward to talking to Mr Brahimi to see what is the position of other influential countries that he talked to in his tour," he said.
"Will they pressure the armed groups that they host and finance and arm in order to abide by such a ceasefire?"
Brahimi, joint envoy of the Arab League and the United Nations, was in Cairo on Tuesday on the latest leg of a regional tour that has already taken him to Turkey and Saudi Arabia, staunch backers of the opposition, and Iran, Syria's closest ally.
He has proposed a truce for the four-day Eid al-Adha Muslim holiday at the end of the month to pave the way for a political process.
Syria's divided rebels have agreed to set up a joint leadership to oversee their battle to overthrow President Bashar al-Assad, after coming under increasing pressure from their foreign supporters to unite, two rebel sources said on Tuesday.
The decision, taken by dozens of rebels - including Free Syrian Army leaders - at a meeting inside Syria on Sunday, aims to improve military coordination among fighters and create a single leadership which they hope outside powers would be prepared to arm with more powerful weapons.
"The agreement has been reached, they only need to sign it now," one rebel source said. The foreign backers "are telling us: 'Sort yourselves out and unite, we need a clear and credible side to provide it with quality weapons'."
Voice of Russia, AFP, Reuters