It marks 100 days since fighting begun between Israel and Hamas, after the group launched an attack on 7 October.
Thousands have gathered in what has become known as 'Hostages Square', a space opposite Israel’s Defense Ministry, which has become synonymous with protests over recent months.
“Today, as we mark 100 days since hundreds of innocent men, women and children were violently seized from Israel, we join as one in demanding their release,” US ambassador to Israel, Jacob Lew said.
It's thought that 111 men, 19 women and two children remain in Gaza, despite a temporary truce in November seeing 100 released.
Israel's prime minister Benjamin Netanyahu has vowed that the war will not end until all are released.