Police have arrested a man after an alleged baby snatch attempt in Timaru.

A 31-year-old man has been arrested in connection with an alleged assault on a woman on Timaru's main street at about 1.30 pm, police say.

When he appears in court he'll face two assault of charges.

The mother screamed "don't take my baby" when allegedly being attacked by the man, Fairfax reported.

She was punched several times but her attacker eventually handed the baby back to as people came to her aid.