The incident comes amid a bitter stand-off between Poland and Israel over how to remember the Holocaust.
Poland's prime minister on Wednesday condemned what he described as a "xenophobic" attack on the country's ambassador to Israel on a Tel Aviv street.
Israeli officials have expressed shock at the attack and said they were investigating the assault on Marek Magierowski on Tuesday.
Polish authorities arrested a 65-year-old Israeli man for allegedly spitting at the Polish ambassador, police said.
The incident comes amid a bitter stand-off between Poland and Israel over how to remember the Holocaust and over demands that Poland pay reparations for former Jewish properties that were seized by Nazi Germany and later nationalised by Poland's communist regime.
Israeli Ambassador Anna Azari was summoned to the Polish Foreign Ministry in Warsaw on Wednesday over the assault.
Michal Dworczyk, the head of Morawiecki's office, said the Polish government expects the perpetrator to be punished.
Polish Prime Minister Mateusz Morawiecki expressed his concern at what he described as a "racist" attack.
"Poland strongly condemns this xenophobic act of aggression. Violence against diplomats or any other citizens should never be tolerated," Morawiecki said.
Israeli foreign ministry spokesman, Emmanuel Nahshon, said the assault was being investigated and expressed "fullest sympathy to the ambassador and our shock at the attack."