Judeh would not say how many activists had been arrested or what their nationality was.
"They received instructions from Hamas leaders, specifically an official from the military wing of Hamas movement who is currently in Syria," He told The Associated Press. He declined to identify who this leader was.
The activists had "Reached the implementation phase of operations that targeted Jordanian institutions and public figures," he said.
After Jordan detained the Hamas members and discovered their arms cache, it cancelled a visit by Palestinian Foreign Minister al-Mahmoud Zahar, who is also the Hamas leader in Gaza, which was scheduled for April 19.
Judeh said he could not specify how many activists were arrested because that would harm efforts to arrest more Hamas militants at large.
"We can't pre-empt the investigation underway because we are in pursuit of others," he said.
After the original discovery of a Hamas arms cache early last week, more weapons were seized, Judeh said Tuesday.
"A detained Hamas activist guided authorities to where they were hidden in a village in northern Jordan."
Syria denies charges
He said the new weapons included TNT explosives, and Swedish-British LAW rockets - light anti-tank weapons.
Last week, a Hamas spokesman in Gaza, Sami Abu Zuhri, denied that his group had smuggled weapons into Jordan.
"Everyone knows that Hamas' battle was, and is, against the occupation of our land. We have no interest in intervening in the internal affairs of others," he said.
Jordan has accused the Hamas activists of threatening the country's national security by smuggling weapons from neighboring Syria. Newspapers ran front page photos last week of the alleged Hamas missiles, detonators and explosives.
Amman has accused Syria before of not stopping Islamic militants from smuggling arms to Jordan, a moderate Arab nation with close ties to the United States and a peace treaty with Israel, signed in 1994.
Syria is home to the Hamas' exiled leadership, including current boss Khaled Mashaal, and has frequently rejected U.S. calls to expel the group's leaders.
Jordan – which once expelled Mashaal for his activities – has called on Hamas to accept an Arab peace plan, which entails full recognition of Israel in exchange for full withdrawal from territory captured in the 1967 and 1973 Arab-Israeli wars.
The United States, which has imposed economic sanctions on Damascus, also accuses Syria of allowing militants to cross into Iraq to fight the U.S.-led multinational force there. Syria has denied the charges.