The loss to Thailand on Thursday effectively ended Malaysia's hopes of qualifying for the semi-finals and they will now play their last two Group B games against Brunei on June 8 and Laos on June 11.
"I'm not sure," Ong told reporters when asked if he would quit. "Let me finish my two remaining games against Brunei and Laos. Probably I'll decide after that and I think it is enough to handle three SEA Games."
Ong, who guided Malaysia to a gold medal at the 2011 Southeast Asian Games, admitted that he was very disappointed with his side.
But, he also conceded that his side had been outplayed by Thailand and Vietnam, who they lost to 5-1 on Tuesday.
"Realistically, Thailand, Malaysia and Vietnam were running for two spots," he said. "So whoever loses the first game against each other will be under pressure.
"And of course, unfortunately we had to play Vietnam first and we lost. And that made it very difficult, moreover, we played not even after 48 hours against Thailand at four o'clock in the afternoon. So it is advantage for Vietnam and Thailand.
"If you ask me, you have to compare four years ago how we prepared our team, two years ago how we prepared our team and you know how we prepared our team this time.
"It's not a blaming game. For me, we have to sit back and look at our program and we have to admit that Thailand and Vietnam are definitely on top of us at the moment."