Syria recalled that it had signed an agreement with the Iraqi and US governments for joint patrols along the border and taken other steps to prevent infiltrations.
"US President George Bush has reiterated his criticisms against Syria despite the steps taken and efforts made by Damascus to protect the borders and support Iraq in its bid to restore security and stability," the official Sana news agency stated on Tuesday.
"President Bush also made new accusations against Syria over Lebanon despite the implementation by Damascus of all relevant clauses of (UN Security Council) Resolution 1559 and its full cooperation with the international commission of inquiry into the assassination of former prime minister Rafiq al-Hariri."
Resolution 1559, passed last September, demanded the withdrawal of all foreign troops from Lebanon.
Syria ended its three-decade troop presence in its smaller neighbour the following April in the face of a wave of protests over al-Hariri's murder in a Feburary bomb blast on the Beirut seafront.
Syria on Monday agreed a format for questioning by a UN team of senior officials who had security responsibility in Lebanon at the time of the blasts.
Bush made his new accusations after White House talks with Iraqi President Jalal Talabani.
Washington has consistently talked up the role of foreign fighters in Iraq and pointed the finger particularly at Syria and its main regional ally, Shia Iran, even though Iraqi officials have also criticised US allies Jordan and Saudi Arabia.