"If Israel carries on with what it is doing, it will be difficult to control matters," Shaath said after a meeting with Egyptian Foreign Minister Ahmed Abul Gheit.
Shaath said the Palestinian side, including the Islamic Resistance Movement (Hamas), is still committed to the period of calmness despite a surge in violence.
On Feb. 8, Palestinian leader Mahmoud Abbas and Israeli Prime Minister Ariel Sharon announced a mutual ceasefire at the Egyptian Red Sea resort of Sharm el-Sheikh.
Palestinian factions have since agreed to observe a period of calmness with Israel, although they stopped short of endorsing a formal truce.
However, violence has flared up over the past few days as militants renewed rocket attacks on Jewish settlements to avenge the killing of an Islamic Jihad commander in the West Bank.