He told MPs Britain had withdrawn its monitors from a prison in Jericho, later occupied by Israeli forces, only because the Palestinian Authority had never met its obligations to protect them.
The withdrawal from Jericho was the trigger for Palestinian attacks on British and other foreign targets in Gaza City and along the Gaza Strip.
Mr Straw told MPs, in answer to a specially scheduled Commons question: "I must emphasise the Government's condemnation of the appalling acts of violence. They are totally unwarranted."
He stressed no locally engaged personnel or British citizens had been harmed in the attacks. The Foreign Office said they had been evacuated earlier.