It's said to have happened on Sidwell Street on Monday 15 July.
A woman was approached by another woman who took her phone and then punched in the nose at around 11pm.
Officers have issued a picture of a woman they wish to speak to as part of their investigation.
New service station could be built near Barnstaple
The scheme includes 22 business units
Devoncast- Murder in Sidmouth with Jeremy Vine, crumbling cliffs and fake tweets for the birds
Murders, rockfalls and swifts among Devon's stories this week
Concern as under half of Devon residents eat their 5-a-day
Worse than national average
Dawlish cliffs could collapse at any time
Newton Abbot MP says action needed
Two murders in Cornwall
They're not linked
Councillor owes more than £3,000 in council tax
They are paying it back at £130 a month
