Salehi arrived Tuesday in Jordan to discuss regional security issues. He's expected to head to Syria from there to address the crisis with Assad, Iran's official Islamic Republic News Agency reports.
Salehi said from Jordan that Syrian opposition groups should negotiate a path for transition. He said he was opposed to outside interference of any kind, stressing it should be Syrians addressing their internal affairs.
Recent airstrikes by the Israeli military against Syrian targets were allegedly meant to stop the flow of Iranian weapons to Hezbollah fighters supporting Assad's regime. Iranian missiles with a range of 190 miles, enough to hit Tel Aviv, were said to have been airlifted to Damascus.
Israel accuses Iran of arming Hezbollah as a proxy force in the Syrian civil war. Hezbollah said last week that some of Israel's claims were meant to broaden the regional conflict.
Salehi said Tuesday that Iran was supporting Syria's national sovereignty and territorial integrity. He blamed Western powers for supporting terrorist groups in Syria that destroyed much of the country's infrastructure.
"We put the blame on them for flow of terrorists into Syria as we are now witnessing," he was quoted by IRNA as saying.
Some rebel forces fighting Assad's government are aligned with al-Qaida.