Theo Walcott’s second-half effort handed Sam Allardyce’s men victory to end the four-match winning run of Rafael Benitez’s side.
The 29-year-old who made his first start in the outing featured for 68 minutes without any shot on target and had little influence in the game before he was replaced by Dwight Gayle.
However, the Magpies skipper has insisted that the Leicester City loanee should not be singled out for blame following the defeat.
"He's a good player and he settled in really well against Arsenal,” Lascelles told Chronicle Live.
"He worked hard for us at Everton and they made it hard for us to play and to give him good service. You can't point the finger at anybody because we win as a team and lose as a team.
"We didn't really get the chance to get the ball down and play or get up the pitch. Sometimes you've just got to hold your hands up and say fair play to Everton because we gave our all."
Injury has restricted Slimani to only three appearances since he arrived at St James' Park from Leicester in January.
The former Sporting CP player will be hoping to deliver a better performance when Newcastle slug it out with West Bromwich Albion on Saturday.