The health ministry reported Saturday that 2,435 new Covid cases had been recorded the day before -- the highest number since March -- driven by the more contagious Delta variant.
There were 326 hospitalisations, the highest since April, although well below the January peak, when more than 2,000 people were being hospitalised daily.
Israel has in recent days rolled out a booster vaccine shot for older citizens, reimposed mask requirements indoors and restored "green pass" restrictions requiring vaccine certificates for entering enclosed spaces such as gyms, restaurants and hotels.
The rise in infections is a step back after Israel's world-leading vaccine campaign drove down new Covid-19 cases from 10,000 a day to fewer than 100.
Protesters Saturday flew a banner that read, "There's no pandemic, it's a con". They held up placards denouncing coronavirus vaccines, with one poster linking vaccines to the Nazis.
Health Minister Nitzan Horowitz told Israeli Channel 12 TV Saturday that he intended to balance public health with livelihood.
"The economy must remain open," he said.
"I don't want to impose a lockdown and I will avoid a lockdown at all costs. Everything is open -- but we need masks and we need vaccines."
Nearly 60 percent of Israel's 9.3 million people have gotten two shots, mostly with the Pfizer/BioNTech vaccine.
But about one million Israelis still refuse to be vaccinated even though they are eligible.
From Sunday, some children between ages five and 11 at risk of health complications will become eligible for vaccines.