He added: "There are challenges on the road but my meeting with President Assad leaves me hopeful that we can make progress together in the interest of both our countries."
Washington and Damascus may disagree on issues such as Syria's alliance with Iran and its support for militant groups like Hamas and Hezbollah, but they have recently found common ground over Lebanon and Iraq, says the BBC's Lina Sinjab in Damascus.
Both countries want to see movement on the Arab-Israeli peace process, our correspondent adds, and this is another area on which the countries can agree.
But analysts in Damascus believe that President Obama's administration needs to quickly deliver something tangible in the coming months to cement the recent progress between the countries.
Syrian-American relations went into deep freeze five years ago when Damascus was blamed for the killing of former Lebanese Prime Minister Rafik Hariri, an accusation Syria has always denied.
Our correspondent says relations were strained even before Mr Hariri's assassination.
Syria has been on Washington's list of state sponsors of terrorism since 1979.
In 2004, the US Congress passed the Syria Accountability Act - which prohibits most American goods from being sold to Syria - and imposed financial sanctions.
The US remains concerned about Syria's support for the Lebanese militant group Hezbollah, says our correspondent.
Washington also wants Damascus to help stabilise Iraq and to influence Iran over its nuclear programme, she adds.
With this nomination, our foreign policy again risks sending the message that it is better to be an intractable enemy than a co-operative, loyal US ally
Ileana Ros-Lehtinen Senior Republican, House foreign affairs committee
In return, the US could end its sanctions against Syria and put pressure on Israel to return the Golan Heights - seized in the 1967 war.
Resolving the Israeli-Syrian standoff could give a major push to a peace accord between Israel and the Palestinians, analysts say.
The appointment of a new American ambassador, Robert Ford, to Damascus has been in the works since the middle of last year, says the BBC's Washington correspondent Steve Kingstone.
"His appointment represents President Obama's commitment to use engagement to advance US interests by improving communication with the Syrian government and people," the White House said in a statement.
If the appointment is confirmed by the US Senate, Mr Ford would "engage the Syrian government on how we can enhance relations, while addressing areas of ongoing concern", the White House added.
But Republicans criticised the nomination as rewarding an enemy.
"With this nomination, our foreign policy again risks sending the message that it is better to be an intractable enemy than a co-operative, loyal US ally," said the top Republican on the House of Representatives foreign affairs committee, Ileana Ros-Lehtinen.
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