ITV said it was targeting a £25mln reduction in overheads in 2017 "against a backdrop of wider economic uncertainty following the EU referendum".
Net advertising revenue in the first half was the same as last year's at £838mln, although other key measures such as profit and revenue were up.
ITV expects net advertising revenue in its ITV Family business to fall about 1% in the nine months to the end of September.
Other media businesses such as Trinity Mirror PLC (LON:TM.) and Daily Mail & General Trust PLC (LON:DMGT) have reported downturns in advertising revenue as the Leave vote on June 23 has hit consumer confidence.
Revenue from activities other than advertising - such as the ITV Studios programme production business - rose 26% to £874mln.
ITV Studios total revenue lifted 31% to £651mln from £496mln a year ago and online, pay & interactive revenue increased 26% to £107mln.
Group adjusted pre-tax earnings before interest and amortisation rose 10% to £438mln. It increased its interim dividend by 26% to 2.4p.
Chief executive Adam Crozier said: "Against a backdrop of wider economic uncertainty following the EU referendum, we have put in place a robust plan to allow us to meet the opportunities and challenges ahead."