The key dispute is over Iran's nuclear program which the West suspects is aimed at developing nuclear weapons. Tehran says it only wants civilian nuclear power.
"We support (a) political solution for issues standing between Iran and the West," Moualem told a news conference with Foreign Secretary David Miliband after the two men held talks on the Middle East peace process and Iran.
"For that, we believe we can play a role but we cannot take decisions on behalf of Iran. They have to take their decisions according to their interest," Moualem said.
He gave no details of what role Syria, a close ally of Iran, could play.
'Syria in a unique position'Major powers have offered Iran trade and other incentives in return for halting uranium enrichment but Iran has not responded.
President Mahmoud Ahmadinejad has shown signs of taking a tougher approach towards the West after he won a disputed election in June which was followed by days of protests that killed at least 20 people.
Miliband said Syria was in a "unique position to influence Iranian policy choices."
"I think it's very, very important that we make clear to the Iranian authorities the significance ... of the policy choices that the new government makes, because there is a very clear offer on the table in respect of its nuclear, but also its wider regional perspectives," Miliband said.
Moualem repeated a longstanding Syrian proposal that the Middle East should be made a zone free of weapons of mass destruction, whether nuclear, chemical or biological.
He said he had asked Miliband to press the UN Security Council to adopt a resolution on a weapons-free zone in the Middle East, which he said would have to include Israel.
"We know that Israel is producing nuclear arms. This is how we can address the Iranian public opinion that there would be no double standard in approaching the nuclear program," he said.
Syria has been at odds with the International Atomic Energy Agency about a site destroyed by an Israeli raid that the United States said was an illegal nuclear reactor. Syria said the site was a non-nuclear military complex.
The US special envoy to the Middle East George Mitchell will visit Damascus on Saturday for meetings with President Bashar Assad and other officials as part of US attempts to improve its ties with Syria and to resume Syria-Israeli talks.
Moualem refused to answer a question from a reporter for Israel Radio who asked whether Syria would stop the flow of weapons from Iran to Hezbollah, a Shiite Muslim group that fought a war against Israel in 2006.