Sir Keir Starmer said the situation was "very serious" and that right approach was through "calm discussion".
The prime minister is seeking to downplay how he intends to react to Trump's threat of tariffs.
The prince is one of seven high-profile claimants that allege the publisher of the Daily Mail and Mail on Sunday committed "grave breaches of privacy".
Independent Office for Police Conduct opens an inquiry into the conduct of the West Midlands force.
A woman who had nearly paid off a £10,000 debt was sent emails suggesting she could apply for new credit cards.