Speaking at the UN General Assembly on the latest situation in Syria, the secretary-general called the new massacre "shocking and sickening", Xinhua reported.
The unarmed monitors from the UN Supervision Mission in Syria were initially denied access to the massacre site in al-Qubayr village in the country's northern Hama province, and "were shot at with small arms" while trying to get there, Ban said.
However, the secretary-general did not give details on whether any of the monitors were injured.
Meanwhile, Kofi Annan, the UN-Arab League joint special envoy for Syria, said Thursday his six-point peace plan to end the country's 16-month crisis has not been implemented.
Annan was speaking at the General Assembly on the latest situation in Syria.
The peace plan, widely backed by the international community and accepted by the Syrian government, had failed to halt violence in Syria, Annan said.
Violence could not be allowed to become part of ordinary life in the Middle East country, he said.
The group of UN observers tasked with examining the reported massacre in al-Qubayr village were blocked from entering the site, said Sausan Ghosheh, spokesperson of the UN Supervision Mission to Syria.
He said the team had been firstly blocked by a military checkpoint and then by the residents of the village, who told the observers that their lives would be jeopardized had they decided to enter the village.