Having recovered from a poor start that had dropped him from second to fourth, Dennis launched an attack on Wehrlein for the lead of the race going into Turn 1 on lap 24 of 36.
But the Porsche driver moved to the right to cover the inside line, forcing Dennis to back off in order to avoid contact, and nearly lose a position to Maserati MSG's Maximilian Gunther in the process.
Dennis kept the pressure up on Wehrlein for the remaining 12 laps but didn't attempt a proper overtaking move again, finishing 0.477s in arrears of the German as the flat-out nature of the race limited opportunities for passing.
Speaking afterwards, Dennis lashed out at Wehrlein for aggressively changing direction into Turn 1, saying his Porsche rival pushed the boundaries in order to keep hold of the lead.
"The manoeuvre with Pascal was ridiculous," the British driver said. "I had to hit so much [brake] pressure to avoid hitting the back of him.
"I don't know how he got away with that, to be honest. It's ridiculous.
"The other two guys [Stoffel Vandoorne and Gunther] did it perfectly and left just enough space for one car which is the rule.
"And then Pascal just completely swerved up to the wall and I had to slam on the brakes halfway up the straight.
"He'd already committed to lifting and at that point you have to leave space and he didn't.
"We can't protest against them because they also have a Porsche powertrain so yeah, bit ridiculous."
He added in the post-race press conference: "Well there's obviously a rule and every driver generally knows the rule.
"I felt like Pascal really pushed the boundaries and I had to do everything I could to obviously not take us both out of the race and I did it with a millimetre spare.
"It was really on the edge and he could have taken us easily out of the race. In the end, he didn't really go by the book."
Wehrlein refused to comment on their near-clash when asked by Motorsport.com, only saying "Not much to comment really. I don't have a lot to say."
Asked if he had spoken to Wehrlein about the incident, Dennis told Motorsport.com: "I mean he didn't say anything. He's not gonna. You wouldn't want to comment if you are in the wrong."
