The 17-year-old opened the scoring on Thursday as an under-strength Manchester City got past the second tier Cherries, with Phil Foden netting a 75th minute winner.
Guardiola fielded a weakened with only a handful of first teamers led by Kyle Walker, Rodri, Riyad Mahrez and Ferran Torres.
Among the youngsters used were goal scorer Delap, Tommy Doyle and Taylor Harwood- Bellis.
“It was a good game, but all our young players played at a high level, Tommy, Taylor, Liam,” Guardiola said. “All of them were really good.
“At 17 years-old, Liam is a different striker to what we have in terms of physicality.
“We see in training how good a finisher he is. Now is the time to be calm and keep working. We are delighted with his performance. He played really well.
“With the situation we have right now, we need players from the Academy.
“We have just 13 players fit. With the problems we have up front, he will stay with us. We will use him.”
City have a raft of players unavailable, including Sergio Aguero, Ilkay Gundogan, Oleksandr Zinchenko and Aymeric Laporte, potentially opening the door for Delap as Guardiola hinted.
The Spanish boss heeded a warning on building up too much hype on Winchester-born England under-age international Delap, who is the son of ex-Premier League star Rory.
“We cannot forget, like with Phil, he is only 17 years-old. He has a lot of things to improve,” Guardiola said.
“We cannot anticipate the progress of every young player.”
Elsewhere in the League Cup on Thursday, Liverpool thrashed Lincoln City 7-2, while Aston Villa got past Bristol City 3-0.