A naked man allegedly grabbed a woman from behind and tried to drag her away during an early-morning attack in Ainslie.

Police say they were called to Duffy Street about 1.20am on Thursday following reports a woman had been assaulted.

The man allegedly approached the woman from behind, grabbed her and attempted to drag her away.

She was able to break free and call for help.

The man is described as having a dark complexion, short stature and a shaved head.

Anyone who can assist police is urged to them via crimestoppersact.com.au.