CCTV footage of an arson attack at a cafe in Canberra's south-west has been released by police.

The footage from March 13 shows the offender smashing a hole in a door of the Weston business and pouring in accelerant, before setting it alight and fleeing.

The March fire was the second time the cafe had been targeted by arsonists within a two-year period.

The property was extensively damaged.

Constable Callum Hughes said police were seeking public assistance after exhausting other avenues of investigation.

"The investigation is still ongoing. We have followed numerous leads but we are at a sufficient point in our investigation with our leads that we have decided to release the CCTV footage to the public," he said.

"What we want is for the public to study the offender closely, check the time and date of the incident, and attempt to recall any suspicious activity, people or vehicles seen around the Cooleman Court shops around midnight on that date in March.

"That little bit of important information to Crime Stoppers could help us jump-start this case and identify this arsonist."

The offender's face is not shown in the footage but police hoped there may be other physical clues, such as the man's clothing, build, posture, or mannerisms, that may help to generate leads.

The man was described as about 165cm tall, with a slight build, round shoulders and right-handed.

Victims 'almost gave up' after cafe arson attack

Owner Mark Dunphy is still rebuilding after the arson attack and hopes to open the cafe soon. ( ABC News )

Cafe owner Mark Dunphy said the latest arson attack, which happened just hours after his family had taken over the site, was devastating.

"We considered many times giving it away and just thinking it is just not worth it," he said.

"But myself and my wife talked about it, and thought it is not fair and we can't let this person win by allowing them to close our business."

The cafe was insured, but because it was not yet operational there was no compensation for loss of earnings.