Police are searching for a man, thought to be aged in his 40s, who is believed to have hurled more than five rocks through the windows of the cafe, which was the scene of a deadly siege late last year.

A NSW Police spokeswoman said police were called to a cafe in Martin Place about 12.30am on Wednesday to reports that the premises had been damaged.

Officers arrived to find a number of windows had been smashed, the spokeswoman said.

"On speaking with a number of people at the scene, we believe a man in his 40s with facial hair and tanned skin may be able to assist with inquiries," the spokeswoman said.

At least six holes could be seen in the glass on the side of the cafe that fronts Martin Place, while shattered glass is scattered inside the cafe.

Police are reviewing closed circuit television cameras, which cover large parts of Martin Place, in a bid to identify the offender.

The cafe was closed this morning as police searched for clues but has now reopened.

The cafe reopened in March, three months after the deadly siege in which two hostages, Katrina Dawson and Tori Johnson, were killed, along with the gunman, Man Haron Monis.

A coronial inquest into the siege is presently being held in Sydney.

"Any attack on that particular location is outrageous," NSW Police Commissioner Andrew Scipione told a media conference on Wednesday.

"We have no links to anything that was related to last year's events.

"We are hopeful we will be able to make ... early arrests.

"It's certainly outrageous that anyone would choose to attack that building."

Police Minister Troy Grant said: "I share the commissioner's disgust.

"There is no rhyme or reason why that premises shouldn't be considered as it is ... it's a significant place in our nation's history now.

"I'm confident  police will bring that matter to an end."

Anyone with information about the vandal has been asked to contact Crime Stoppers on 1800 333 000 or to visit the Crime Stoppers online reporting page.

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- with Emma Partridge