JERUSALEM (Reuters) - Thousands of Israelis rallied in Tel Aviv on Saturday to mark the 20th birthday of Naama Levy, who has been held hostage in Gaza since Oct. 7, and to call for an immediate ceasefire in the war with Palestinian militant group Hamas.

Releasing balloons and chanting to the beat of drums, protesters shared bite-sized cupcakes decorated with birthday candles, while demanding the release of all hostages taken by Hamas following its deadly raid on Israel eight months ago.

"She needs to be here with her family, with her friends," said Yoni Levy, 52, Naama's father, wearing a shirt emblazoned with his daughter's image.

On Thursday Naama's elder brother Amit shared memories of his sister with Reuters, pointing to her smiling face in a magazine picture with the headline: "Bring Her Home".

"I really can't wait to see this smile when she comes back soon," he said.

A video of Naama posted by Hamas militants on Oct. 7 - showing her with hands tied behind her back, dressed in tattered pyjamas and visibly injured - went viral on social media.

She had just begun her duties in the Israeli Defense Force when she was seized, along with four other female army conscripts, in the raid that triggered Israel's war on Gaza.

Hamas killed around 1,200 people in the raid and seized more than 250 hostages. Israel's response has left Gaza in ruins and killed more than 37,400 people, including 101 in the past 24 hours, according to Palestinian health authorities.

(Reporting by Emily Rose; Editing by Mark Potter)