Officers say they have also established the identities of other suspects linked to the incident in the Polish capital at the end of last week.
The detained men are “two Dutch nationals of Armenian origin,” a spokesman for Warsaw police said on Wednesday, as cited by state news agency PAP.
Meanwhile, “a person of Palestinian origin residing in one of the Benelux countries” has been named as another suspect in the case.
No Pole is suspected of being involved in the attack, officers also said.
The Warsaw police spokesman, Sylwester Marczak, was quoted as saying that “further investigation will be carried out as part of international cooperation.”
Four Israeli students were assaulted and injured as they were leaving a Warsaw night club at around 5 a.m. on Saturday, according to media reports.
Two of the students required medical attention after the attack, the rp.pl website has reported.
The Polish foreign ministry has condemned the incident in a Twitter post.
It said: "The Polish Ministry of Foreign Affairs strongly condemns any acts of aggression committed by (and against) foreigners in Poland.”
It added that the attack was being investigated by police.
“We oppose any forms of violence,” the Polish foreign ministry said.
Meanwhile, the Polish ambassador to Israel, Marek Magierowski, has called the incident “a despicable act of barbarism” and said on Twitter that “there’s no justification for violence.”