A middle-aged woman was indecently assaulted while walking through a park in Melbourne's inner north, police say.

The attacker, a man believed to be aged in his mid 20s, approached the woman in De Chene Parade, Coburg, about 8am last Tuesday, and asked for directions.

The man assaulted the woman, 53, and ran off down the street towards Newlands Road, a police spokeswoman said.

The woman tried to run after her attacker but she lost sight of him.