Della Valle said Germany, Vodafone's biggest market, was underperforming, while Spain, which has suffered cut-throat competition in recent years, was under strategic review.
Underscoring the pressures on the business, Vodafone said it would generate 3.3 billion euros ($3.6 billion) of cash this financial year, down from 4.8 billion euros in the year to end-March 2023.
Analysts had expected 3.6 billion euros.
For the year to end-March, pressures in Germany and higher energy costs resulted in a 1.3% decline in Vodafone's group core earnings to 14.7 billion euros, missing its own guidance.
Vodafone has already started to cut jobs in its big markets, shedding 1,000 in Italy earlier this year, while a media report said it was looking to cut around 1,300 in Germany.