Ronaldo was dropped for the game at Stamford Bridge after refusing to be introduced as a substitute in Manchester United's 2-0 win over Tottenham Hotspurs in midweek and then storming down the tunnel before the game had concluded.
Casemiro's stoppage time header salvaged a point for the Red Devils against Graham Potter's men after Jorginho's late penalty had Chelsea in front.
But United could have walked away with all three points had they made the most of some clear cut chances that fell their way in a dominant first half, with Marcus Rashford and Antony guilty of profligacy.
"As always, he can score a goal," Ten Hag said of his missing talisman.
"He's valuable for us and we need him, it's clear, and I think you see it also in this game. He can finish off, it's obvious."
"I think I've said enough about the situation," the Dutchman added when asked when Ronaldo will be called upon again.
"Let's focus on the game. It was a good game from my team and I have to really compliment my team for this.
"If you can deliver this after four games in 10 days, if you then dictate this first half and in the second half you are well organised and then fight back, I think that has to be the focus."
