Israel's public broadcaster Kan said it had filed a complaint to the Swiss police, saying a protester made a "throat-slitting gesture" and spat at members of the country's delegation during the Eurovision opening ceremony on Sunday.
The Eurovision Song Contest week kicked off in Basel with a 1.3-kilometre long parade through Switzerland's third-biggest city, with contestants, including Yuval Raphael for Israel, travelling along the route in vintage trams and buses.
A number of pro-Palestinian demonstrators were among the crowds lining the so-called "turquoise carpet" route, waving placards and Palestinian flags, and using megaphones.
Kan said on its website that it had "filed a complaint this afternoon with Swiss police following an incident in which a young man wearing a keffiyeh and holding a Palestinian flag made a throat-slitting gesture toward Yuval Raphael and members of the Israeli Eurovision delegation".
"The corporation also contacted the European Broadcasting Union, requesting that action be taken to identify the individual who made the gesture and spat at members of the delegation."
Eurovision is organised by the EBU, the world's biggest public service media alliance, of which Kan is a member.
AFP has sought a comment from the Basel City police and from the EBU.
Fans and demonstrators alike were able to get up close to the trams as they passed through Basel.
More than 1,300 police officers were being placed on duty in Basel during Eurovision week, while video surveillance cameras have gone up around the fan zones such as the Messeplatz square.
Basel's emergency services said the parade "went off without any significant problems" from their point of view.
"The police were able to stop around 150 people at the Messeplatz through their presence and thus prevent the official event from being disrupted," a brief statement said.
Last year's contest in Malmo, Sweden saw street protests over the Gaza war. Israel's entrant Eden Golan performed under tight security amid threats, and was largely confined to her hotel.
This year's Israeli entrant Raphael survived the October 7, 2023 attack on Israel that sparked the war in Gaza, hiding beneath dead bodies as Hamas gunmen attacked a music festival, killing hundreds.
More than 70 former Eurovision competitors last week called for Israel to be banned over the war in Gaza, which has claimed tens of thousands of lives.