An embassy statement also suggested the assassination was timed by unidentified elements to frustrate calls around the world for engagement between Syria and Western powers, which have notably centred on how Damascus could help quell violence in Iraq.
"The Embassy of Syria in Washington strongly condemns this heinous terrorist act and extends its condolences and prayers to the family of the deceased," said the statement.
"Unfortunately, this awful act surfaces as yet another proof indicating that every time the political forces in Lebanon, with anti-Syrian agendas, are weakened, a trigger is pulled to re-inflame and instigate the streets against Syria.
"This charade of blaming Syria for every malicious event in Lebanon has been exposed a long time ago and is, simply, losing all credibility," the embassy statement said.
"Syria is outraged by this terrible act. In a time when the international community is advocating more engagement with Syria, such an act only stands to undermine these initiatives."
The statement also suggested the killing was timed to coincide with a looming United Nations Security Council decision on forming an international tribunal on the killing of Lebanese ex-premier Rafiq Hariri.
"It's no coincidence that Pierre Gemayel was assassinated on the day the Security Council is discussing a Lebanese issue," the statement said.
It pointed out that anti-Syria lawmaker and journalist Gibran Tueni was killed in the wake of discussion on the second report on the Hariri assassination by Detlev Mehlis, the German prosecutor appointed to investigate the Hariri murder.
"It is obvious that whenever the world attention is focused on Lebanon, a terrible crime occurs in an attempt to accuse Syria," the embassy statement said.
Earlier in Damascus, an official source quoted by the state news agency SANA condemned the killing of Gemayel as "a crime aimed at destabilising" its neighbour.
Gemayel was assassinated in a northern suburb of the Lebanese capital, in the latest in a spate of attacks to target anti-Syrian politicians, a security source in Beirut told AFP.
The son of slain Lebanese ex-prime minister Rafiq Hariri on Tuesday accused Damascus of being behind the assassination. "We believe that the hands of Syria are all over the place," he said in an interview with CNN.

Copyright AFP (Agence France-Presse), 2006