"You put out fires with a bit of water, not with petrol," the former Espanyol and Athletic Bilbao coach told a news conference on Friday after taking charge of his first training session.
"I believe the players enjoy playing well and that's what we will try to do. We have to take it step by step but win.
"We are under pressure and I am aware of that."
Valverde was appointed this week in place of Mauricio Pellegrino, who was sacked despite leading the team into the last 16 of the Champions League.
Unpopular president Manuel Llorente fired the Argentine after last weekend's 5-2 defeat at home to Real Sociedad which left Valencia in 12th place and in danger of missing out on a place in Europe next season.
Valencia, who have 18 points from 14 games, play at struggling Osasuna in La Liga on Saturday (2100 GMT). (Reporting by Iain Rogers, editing by Clare Fallon)