Among others at the meeting on Thursday, Gilli Roman, who is also a German citizen, recalled his sister-in-law Carmel, who was abducted from Kibbutz Beeri on October 7 last year.
"We know little about Carmel's situation," said Roman. "We hope she is alive. But we don't know."
The representatives of the Security Council and several other UN member states present, including Germany, promised to continue their efforts to secure the release of all hostages.
Hamas and its supporters killed around 1,200 people, including around 800 civilians, in the attacks on October 7. They also kidnapped more than 200 women, men and children.
Out of all the hostages, 105 of them were released after almost two months, following an agreement between Israel and Hamas. The fate of the remaining hostages is unclear.
According to Israeli estimates, around 100 of them are probably still alive.