Howe was left frustrated after his team let slip another two-goal lead, with Newcastle now dropping 13 points from winning positions this season after Nick Woltemade's first-half double was cancelled out by Chelsea's second-half comeback.
But Newcastle felt aggrieved when Trevoh Chalobah made a robust challenge on Anthony Gordon in the second half, with appeals for a penalty dismissed by the referee and VAR.
"I think it's a clear penalty. I think anywhere else on the pitch, that's a free kick," Howe told TNT Sports.
"I think the player has got into Anthony aggressively, too aggressively in my opinion, so I think it's a stonewall."
The Premier League match centre said a penalty was denied because contact from Chalobah on Gordon was deemed to be "side-to-side in a shielding action" and because the ball was "within playing distance" - an explanation Howe rejected outright.
"No, because it's not. I think the defender's only look is Anthony, not the ball, and I think it's too aggressive," he added.
Chelsea boss Enzo Maresca said he did not see it as a penalty but was happy to take a point under the circumstances.
"I think there are not many teams that are 2-0 down at half-time - against this team in this stadium - and they can come back," he said.
"Today I'm very happy because I feel proud of the players. It's not easy at 2-0 down to show character and come back... The game was 50-50 and enjoyable for the fans."
Newcastle let it slip
Howe will lament his side failing to win at St James' Park, where Reece James and Joao Pedro salvaged a point for Chelsea.
Newcastle have now gone 10 Premier League games without a clean sheet to leave them 11th and could slip down the table depending on results over the rest of the weekend.
"We've not done our jobs and followed through and won today, but that's something we're reflecting on and analysing all the time," Howe said.
"I think we've been in a good place since the last international break. When we returned, and we beat Manchester City (in November), I think we've seen a big upturn in the consistency of performance.
"We had the dip at Sunderland (a 1-0 defeat), but that apart, I think we've been very good. I'm positive about the team and the trajectory we're on. I'm disappointed with the results."