Three protesters from A22 Network, who interrupted the Swedish final of Let's Dance on TV4 last month, knelt on the track about 10 metres from the finish line, stretching a banner across six lanes, forcing most of the field to run through it.
Warholm, running out in lane eight, was not affected.
"It is permissible to protest, but this is not the way to do it," Warholm told Norwegian broadcaster NRK. "It is disrespectful to those who are here to do a good job.
"I must honestly admit that I'm pissed off."
The double world champion, who slapped his thighs and let out a loud whoop during the introductions, ran blind in lane eight en route to a time of 47.57 seconds.
While he was a way off his world record of 45.94 set at the 2020 Tokyo Olympics, two victories in two races bodes well for the World Athletics Championships scheduled for August 19th-27th in Budapest after an injury-riddled 2022 season.
It was not a day for records with the weather - driving rain for most of the night and a chilly 15C - playing spoiler. The crowd at Stockholm Stadium huddled in red rain ponchos.
"I felt very good before the start but the conditions make it a little bit more challenging, but I felt I had to get in and got to post another good time, so I am very pleased," Warholm said. "I am 100% exactly where I want to be."
Freweyni Hailu (22) led a trio of Ethiopians in the top three spots in the women's 1,500m, surging into the lead with half a lap remaining to finish in 4:02.31.
"The victory is great but the competition was not ideal due to the weather. But we have to adapt to all conditions," Hailu said. "I believe in more victories to come this season.
Kenyan Beatrice Chebet (23) won a tactical women's 5,000, opening a yawning gap on the field with 300 metres remaining to clock a season's best 14:36.52.
"The first thing was to get the win today and the second was to fight with these conditions," said Chebet, silver medallist in the event at the 2022 world championships. "Yes, the weather was not really good but you need to run in any conditions."
Olympic champion Soufiane El Bakkali (27) of Morocco won the men's 3,000m steeplechase, beginning his celebrations with 50 metres remaining to win in 8:09.84.
With Lamecha Girma (22) of Ethiopia breaking the steeplechase world record last month in Paris, there could be a thrilling battle between the African pair at the worlds in Hungary.
Akani Simbine (29) of South Africa, a top-five finisher in the last three world championships, was not really challenged en route to victory in the men's 100 metres in 10.03 seconds.
"I just wanted the win here and I got it so glad at the moment and let's go building up on it," Simbine said. "In such conditions, I think the time was fast... I do not like rain, I was cold. I just went there and ran."
