The Magpies were beaten 2-0 by Jurgen Klopp's men at Anfield on Saturday, courtesy of goals from Salah and Mane.
Despite putting up their best effort, Lascelles admits his side were overrun by 'world-class' players.
"We knew it was going to be tough going to Anfield. We stuck to our gameplan, but unfortunately they opened us up and scored their first," the 24-year-old said.
"At half-time we thought we'd come in, refresh and listen to the manager, who told us to stay in the game as long as possible and try to put more pressure on them at the end.
"But then they scored again, and up against a team like this it becomes really difficult because they have world-class players."
He continued: "They're probably up there with the best front threes in Europe.
"We played against them up at St James' and we managed to get a good result then - and that was with Coutinho at the time.
"They're all world-class players, and I thought during the first 40 minutes we did well against them. Salah likes to run, he's pretty smart."