Iranian President Mahmoud Ahmadinejad met Syrian President Bashar al-Assad in Damascus on Saturday.
The official Syrian news agency did not give any details of the meeting between Ahmadinejad and Assad, but Syrian political commentator Ayman Abdel Nour said Washington had been unsuccessful so far in driving a wedge between the leaders.
"The Syrians have assured the Iranians that any progress in ties with the United States or in peace with Israel will not come on the expense of Tehran," he said.
The alliance between Syria and Iran started soon after the Iranian Revolution in 1979, when Syria intensified its ties with Iranian backed clerics in Lebanon and supported Iran in its eight year war with Iraq that broke out in 1980.
Almost ten years of U.S. supervised talks between Israel and Syria collapsed in 2000. Turkey mediated four rounds of inconclusive discussions between the countries in 2008.
At the centre of the talks was the Golan Heights, which Israel has occupied since the 1967 Middle East war. The strategic territory, which overlooks Damascus and Syrian-populated Galilee region that Israel claims.