The incident happened at the offices of Public Initiative For Prevention of Suicide and Self Harm (PIPS) on the Antrim Road some time between 21:00 BST on Friday and 10:00 on Saturday.
Brian Maguire, the charity's chief executive, said three windows at the premises had been smashed.
People responded to an appeal on social media to help with a clear-up, he said.
"It has been quite upsetting for us and our volunteers," he added.
"We have some very vulnerable clients that come to us and our main mission this morning was getting our building sorted for our clients coming at two o'clock and that's what we have done."
He said he did not believe at anything had been taken.
The offices of a suicide prevention charity in north Belfast have been ransacked during a burglary attempt.