"We express grave concerns over the fact that South Korea has armed Israel with conventional weapons," the local branch of Amnesty International said.
"South Korea must therefore urgently suspend its arms transfers to Israel until the Middle Eastern state stops committing serious human rights violations."
The Seoul office added that it has launched a campaign to collect signatures to convey the message to the South Korean government.
A letter expressing concern over the sale of weapons from Seoul to Israel has also been delivered to South Korean Foreign Minister Yun Byung-se recently, it said.
As of Wednesday, the human rights advocacy group estimated that more than 1,300 people have died and 7,500 have been injured in Gaza since the Israeli operation began on July 8.
The Israeli military has used a wide variety of conventional weapons, including guns, bullets and missiles, to kill innocent civilians, the group said, adding that South Korea has sold 22.7 billion won (US$22 million) worth of such weapons to Israel since 2008.
The U.N. estimates that of the hundreds killed in Gaza, 78 percent have been civilians and 21 percent of them have been children.
The latest Israeli attack on a U.N. school in Gaza sheltering civilians early Wednesday has drawn fire from the U.N. Secretary-General, Ban Ki-moon, who condemned the killings as "outrageous" and "unjustifiable."
