US President George W Bush has insisted that Israel has the right to defend itself, in his first public comments since an Israeli air strike against a target inside Syria.
Syria says the target of the strike was a refugee camp
But Mr Bush also said he had urged Israeli Prime Minister Ariel Sharon to try to avoid further escalating tensions in the Middle East.
BBC Washington correspondent Rob Watson says Mr Bush's comments were a diplomatic balancing act designed to reassure Arab allies but to avoid any criticism of Israel.
Israel says Sunday's air strike targeted a training camp run by Islamic Jihad, the group it accuses of carrying out a suicide bombing in the coastal town of Haifa that killed 19 people the day before.
Syria insists Islamic Jihad has no camps in the country, and has tabled a draft resolution at the United Nations Security Council condemning the Israeli action as "military aggression".
ISRAEL AND SYRIA - OLD FOES
Went to war in 1948, 1967 and 1973
Israeli attacks on Syrian forces in Lebanon go back to 1982, with new strikes in 2001
Israeli warplanes buzzed a presidential palace in Syria in August in what was seen as a warning
Speaking in Washington, Mr Bush said: "Israel must not feel constrained in terms of defending the homeland.
"However, I said that it's very important that any action Israel take should avoid escalation and creating higher tensions."
The president condemned the "needless murder" of the Haifa bombing, and called on the Palestinian Authority to fight what he called the terrorists trying to prevent the creation of a peaceful Palestinian state.
Mr Bush did not say whether the United States would veto a UN resolution condemning the attacks in Syria.
But the US has accused Damascus of being on the wrong side in the war on terror, and our correspondent says Washington is likely to have little time for a resolution that does not also condemn the attack in Haifa.
The US ambassador to the UN, John Negroponte, has said there is no need for the resolution, and that instead Syria needs to dismantle the terrorism within its borders.
"We have been clear of the need for Syria to cease harbouring terrorist groups," Mr Negroponte said.
The US has often used its veto to block resolutions condemning Israel because it says others involved in the Middle East conflict should also be included.
Syria and Israel are long-standing enemies, and have been technically at war since Israel's founding in 1948, with tensions further exacerbated by Israel's occupation and illegal annexation of the Golan Heights.
Israel said the target of the air raid was the Ein Saheb training camp, 22 kilometres (14 miles) outside Damascus, which it said was used by several militant Palestinian groups, including Hamas and Islamic Jihad.
Syrian media have described Ein Saheb as a Palestinian refugee camp.