The pair worked together for several seasons at Wolves.
The Hammers go to Fulham on Wednesday night and Nuno said: "I'm really pleased to see him doing so well. Me and Raúl Jiménez worked together and he's a player I have big admiration for.
"I'm delighted to see him playing well and enjoying himself, especially after this traumatic episode he had (with his head injury).
"The threat and character he's showing every day, I say 'Well done'."
West Ham winger Adama Traore will face his former Fulham teammates tomorrow night.
Nuno added: "I think the squad has accepted him really well. He has brought new energy to us.
"We've been trying every day to help him. He's had spells in the game, but of course ahead of him he has two players at the top of their game (in Jarrad Bowen and Crysencio Summerville), and he's patient enough to realise his chance will come."