More than a thousand people demonstrated against the IDF's Operation Cast Lead in Tel Aviv's Rabin Square on Saturday evening.
In response, about 600 activists gathered in the same place to show support for the army and for residents of the South.
Witnesses told The Jerusalem Post that many of those demonstrating against the operation wore keffiyehs and waved combined Israeli and Palestinian flags.
People supporting the operation, who organized a counter-demonstration upon learning of the left-wing event, chanted "IDF, we are with you!"
The group included members of the Im Tirzu student organization, which has a stated aim of "returning Zionism to the Israeli consciousness," as well as Likud activists.
Im Tirzu spokesman Erez Tmidor told the Post that police were preventing participants in the counter-demonstration from marching from Rabin Square to the city's Cinematheque.
Police had "cornered hundreds of people into an area on the corner of King David and Ibn Gvirol streets near the square" and were refusing to let them join the march, Tmidor said.
Police said they arrested four of the counter demonstrators for disturbing the peace.
Yaakov Lappin contributed to this report