His comments came after Saudi Arabia said earlier this week it would be willing to send troops as part of what Riyadh claims is a US-led military campaign against Daesh (ISIL) extremists.
Al-Muallem said conventional wisdom and logic would suggest the idea of Saudi troops in Syria is far-fetched, but that "with the crazy Saudi leadership nothing is far-fetched."
"Any ground intervention in Syria, without the consent of the Syrian government, will be considered an aggression that should be resisted by every Syrian citizen," he told a news conference in Damascus.
"I regret to say that they will return home in wooden coffins," the Associated Press reported.
Al-Muallem's comments capped a week that saw the collapse of UN-led efforts to launch indirect peace talks between the Syrian government and an opposition delegation in Geneva.
The talks broke down in large part because of pressure from Saudi Arabia and Turkey on opposition groups to withdraw, after Syrian army made strategic gains on the outskirts of Aleppo, once the country's largest city.
Al-Muallem said the government advances signaled that the five-year-old Syria war is nearing its end. "I can say, from the achievements for our armed forces ... that we are now on track to end the conflict," he said. "Like it or not, our battlefield achievements indicate that we are headed toward the end of the crisis."
Opposition representatives have said they cannot be expected to negotiate in Geneva at a time when the Syrian government and its allies, including Russia, are escalating attacks on militant strongholds.
Al-Muallem dismissed the representatives of the Saudi-backed militants in Geneva, suggesting they followed orders from Saudi Arabia and were "not real Syrians."
He alleged the opposition never intended to negotiate seriously. "They did not come to have dialogue, they did not have such orders," he said.
Al-Muallem said the Syrian government was ready to have dialogue with Syrians, but without preconditions.