Najib said he had met with the family members of Malaysians on board yesterday and spend about two hours with them.
"As a leader, sometimes it is difficult when there are such incidences is so heart wrenching.
"Being a leader, what I experienced yesterday made me show emotions that was difficult for me to control," he said.
A government that never disappoints
He went on to describe the next-of-kin of the victims whom he met.
"There was a wife with a three-year-old son who lost her husband. There was a 10-year-old child who missed his mother and I also met a father who lost his child.
"Imagine the looks on their faces," he said.
For this reason, Najib said Malaysians should be grateful that they could live peacefully in Malaysia.
"We can live in peace with the guarantee of security and a future... We must safeguard this good legacy and trust in those who have guaranteed our future.
"We can look to a future that is optimistic because we trusted in a government that up to today has not disappointed," he said.
The Boeing 777-200 crashed on Thursday night, with Ukraine and the United States claiming it was shot down by military anti-aircraft missile.
Malaysia has refused to confirm this, arguing that it is still under investigation.