Deulofeu produced a finish similar to his stunning effort at Wembley earlier this month in Watford's FA Cup semi-final win over Wolves to give his side an early lead.
The Spaniard then sealed the points for the Hornets with 10 minutes to go before Huddersfield substitute Karlan Grant headed a stoppage-time consolation.
"They showed their pride and I want to be very respectful with that team. They're living a very difficult situation and for Huddersfield today it's not an easy game. It's difficult to play in these circumstances.
"In the beginning we had possession, we had control of the game, scoring the first goal and after that we tried to kill game, but didn't do it.
"In those minutes we were suffering because in one set piece, or in one counter attack they could score."
On Deulofeu, he also said: "He's scoring important goals and very good goals.
"All goals are good for me, but in this moment I think Gerard is scoring and he is living an important moment for him and for the team, helping the team with his goals.
"In other moments he didn't score, but always he plays with good commitment and he tries to help the team."