National police spokesman Brig Gen Boy Rafli Amar said the men were captured yesterday by an anti-terror squad in Surabaya, the provincial capital of East Java.
Amar said the militants, identified as Priyo Hadi Purnomo, Jefri and Feri Novendi, had planned an attack during the current Muslim fasting month of Ramadan.
He said three homemade bombs, a suicide bomb vest, guns and high-explosive materials were seized from the group. Purnomo was prepared to be a suicide bomber, he said.
Amar said the men wanted to imitate a January 14 attack in Jakarta that killed eight people, including four militants.
Indonesia, the world's most populous Muslim nation, has seen a spate of deadly attacks by Islamic militants including bombings on the tourist island of Bali in 2002 that killed 202 people, mostly foreigners. Smaller, less deadly strikes in recent years have targeted government authorities, mainly police and anti-terrorism forces.