The decision was reached at a meeting of the alliance at Awami League president's office in Dhanmondi on Friday. 14-party asked the foreign ministry to take necessary measures.
Awami League Presidium member Mohammad Nasim told reporters after the meeting, "What is going on in Gaza cannot be an act of a civilised nation. This is the most heinous crime in history. It is unfortunate that some nations are supporting these attacks."
"In the holy month of Ramadan they are everyday shedding blood there," he said.
The alliance thanked Prime Minister Sheikh Hasina for the victory of Bangladesh in the maritime boundary dispute with India.
"Her determination and timely actions have brought about this victory," Nasim said.
He said the alliance would hold rallies at all divisions in September and will hold a delegates’ conference in Dhaka.
Senior leaders of the alliance were present at the meeting.