Police are investigating an alleged assault in Canberra's south overnight.

Officers attended a house in Cromwell Circuit in Isabella Plains about 2am, after receiving a report a man had been badly assaulted by two men.

The alleged victim spoke to police at the scene, but is yet to give a formal statement. A police spokesperson said the man did not require transportation to hospital.

Police are urging anyone who may have witnessed the incident or any suspicious activity around Cromwell Circuit to contact Crime Stoppers on 1800 333 000, or online at www.act.crimestoppers.com.au.