Syria's Foreign Minister Walid al-Mualem was quoted by the country's state news agency (SANA) saying Washington should reject the Israeli accusations that it had given the armed Lebanese Shiite political group the missiles, Reuters reported.
"We warn the United States not to adopt false Israeli allegations and we say what destabilizes the security of the region is in fact beefing up Israel with all the latest U.S. weaponry and abetting Israeli allegations at our expense."
Israeli President Shimon Peres last month accused Syria, which is allied to Iran, of sending Scuds to Hezbollah. Syria says it only gives Hezbollah political backing and that Israel may be using the accusation as a pretext for a military strike.
Israel and Hezbollah fought a month-long war in 2006 during which the guerrilla group fired thousands of mostly short-range Katyusha missiles into the Jewish state. Israel said Damascus and Iran were arming Hezbollah, but did not attack them.
Israel is worried the guerrillas have replenished their arsenal to attack it on Iran's behalf should Tehran's nuclear sites come under attack.
Hezbollah leader Sayyed Hassan Nasrallah's office reiterated that his group would neither confirm or deny whether his guerrilla group had received any weapons.
"To own any weapon is our legal, moral and humanitarian right because we need it to defend honorable people oppressed and threatened by the cancerous existence of the State of Israel," he told a committee responsible for logistical and financial support for the Iranian-backed group.
Nasrallah said in an interview broadcast on Thursday to Kuwaiti television al-Rai that he did not think the Israeli accusations were a pretext for war.
Speaking in the Estonian capital on Thursday ahead of a NATO meeting, Secretary of State Hillary Clinton dodged questions about whether Iran might have given Syria Scud technology ultimately destined for Hezbollah.
"We have expressed directly to the Syrian government ... in the strongest possible terms our concerns about these stories that do suggest there has been some transfer of weapons technology into Syria with the potential purpose of then later transferring it to Hezbollah," Clinton said.
In 2007, Israeli warplanes destroyed a desert complex in Eastern Syria that the United States, Israel's chief ally, said was an undercover nuclear installation.
Syria said the site was a regular military installation and did not strike back, reserving the right to respond in the appropriate place and time."
Syria and Iran have also accused Israel of assassinating a top Hezbollah commander in Damascus in 2008.