NEVE DEKALIM, Gaza Strip – Tens of thousands of Israelis gathered yesterday in the Gaza Strip’s largest settlement bloc to rally against the government’s plan to withdraw from the area, trying to maintain a carnival-like atmosphere of defiance despite a Palestinian rocket attack.

Though the crowd filled the central lawn at the largest Gush Katif settlement, Neve Dekalim, the turnout of about 40,000 was less than half the number the settlers expected, and some residents dismissed the prediction that thousands of the visitors would stay to join resistance to the pullout, set for July or August.

As the rally was in progress, a homemade Qassam rocket and two mortar shells fired from a nearby Palestinian area exploded nearby, slightly wounding a soldier. Though such attacks had diminished since a February 8 ceasefire and deployment of police by Palestinian leader Mahmoud Abbas, barrages have picked up in recent days, and the Israeli military is warning of a general upsurge in violence in Gaza.

Demonstrators at the Gaza settlement said the rocket attack showed that Prime Minister Sharon’s pullout plan would only encourage more violence. Mr. Sharon “is retreating under fire and with his tail between his legs,” said Benni Elon, a member of parliament from a pro-settler party.

Despite Mr. Abbas’ efforts to rein them in, the militants are likely to step up attacks as the summer pullout approaches, trying to show that they are forcing the Israelis to leave. Also, the Israeli military is warning that militant groups in the West Bank are preparing a new round of violence for the fall, after the pullout, to try to expel the Israelis.

Mr. Sharon’s plan to evacuate all 21 settlements from Gaza and four from the West Bank has the support of about two-thirds of his people, according to polls. But the opposition, based on religion and ideology, is tough and loud.

Adopting orange as the color of their protest, settlers and their backers with orange flags, banners, and T-shirts gathered on a warm, sunny day in Neve Dekalim, a village of red-roofed houses with about 2,500 settlers next to Khan Younis, a poverty-stricken Palestinian city of 100,000, with a refugee camp of 60,000 fenced off from the settlement.

Explaining his pullout plan, Mr. Sharon said maintaining 21 settlements with 8,500 residents among more than 1 million hostile and poverty-stricken Palestinians in Gaza was an untenable proposition. Also, pulling out of the four small settlements in the northern West Bank would solidify Israel’s hold on the main settlement blocs where most of the 235,000 West Bank settlers live.

Though many of the settlers were strident in their denunciations of Mr. Sharon and his policies, leaders insisted resistance would be nonviolent.

Sara Lemann, from New Orleans, La., worried that the current pullout would lead to evacuation of more West Bank settlements. “I think we all feel that we could be next,” she said. “I feel Jerusalem could be next.”

Reuma Harari, who left the West Bank with her three children early in the morning to attend the Gaza rally, seemed as bewildered as angry. “It’s as if a black hole were opening up,” she said. “It imparts a sense of great instability.”