At about 20:30 BST on Friday a man was pulled out of his car on the New Lodge Road by two youths who drove off in it.
It was driven a short distance and set alight. Firefighters who came to put the fire out were attacked with bricks, a baseball bat and an iron bar.
One of the firefighters suffered bruising to her arm and ribs, the other sustained bruising to his leg.
Group Commander Geoff Somerville said attacks on fire crews had to stop.
"Our firefighters work tirelessly for the community to save life and protect property, they do this on a daily basis, responding to emergency calls without fear or favour," he said.
"On this occasion they had to withdraw and that's a worrying concern.
"Any delay resulting from people obstructing or attacking firefighters could mean the difference between life and death."
SDLP assembly member Alban Maginness said those responsible "are a disgrace to us all".
"Those who were behind it clearly do not reflect the majority of people who live here," he said.
Sinn FÃ©in Councillor JJ Magee said it was a vicious attack.
"I would appeal for anyone involving themselves with such activity to reflect today that it could be your family in need of rescue by emergency services and such disgraceful actions put lives at risk," he said.
Two firefighters have been taken to hospital after being attacked by a group of youths in north Belfast.