Police urged people in the Antrim Road area to remain vigilant and report any suspicious objects.
A police spokesman said searches were carried out after the reported attack on Saturday evening.
However, nothing has yet been found.

The boy, 16, suffered serious injuries in the attack in Chatham High Street at the junction of Upbury Way between 19:30 GMT and 20:15 GMT on Friday.
Two men aged 18 and 19-years-old have been arrested following the incident and are currently in custody.
The 16-year-old and the two men in custody are believed to be known to each other, Kent Police said.
The force said it was seeking to speak to a further two suspects.
Searches have been carried out in north Belfast after police received information that an explosive device was thrown at one of its patrols.
[NEXT_CONCEPT]
A teenage boy is in a serious condition after he was allegedly struck by two cars then chased and assaulted.