"Fighters should be in good physical condition, have a strong faith and be ready to die," Ahmad Soebri Lubis, secretary-general of the Islamic Defenders' Front, told Reuters by telephone.
"They will be provided with a one-way ticket until we defeat Israel."
Lubis said the group would start recruiting at its Jakarta headquarters in the next few days, and would send volunteers for training at camps in Indonesia to prepare them for the "battleground".
He said the group has in the past sent volunteers to Iraq and to Afghanistan.
Many Indonesians support the Palestinian cause and are opposed to U.S. policies in the Middle East, particularly the U.S.-led invasion of Iraq.
The Indonesian government on Sunday joined widespread international condemnation of Israeli attacks on the Gaza Strip which began with air strikes on Saturday.
Israel said the strikes, that have killed 307 Palestinians, were launched in response to almost daily rocket and mortar fire from the Hamas-ruled Gaza Strip after the Islamist Hamas group ended a six-month ceasefire a week ago.
More than 1,000 people rallied in Jakarta on Monday to protest against the air strikes.
The vast majority of Muslims in Indonesia are moderate, but groups like the Islamic Defenders' Front, usually known by its Indonesian acronym FPI, have grown more vocal in recent years.
In June this year the group attracted widespread condemnation when its supporters beat up and injured several people at a peaceful interfaith rally.
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