"He didn't address us today, but he did address the team before so that was taken care of," Bulls swingman Justin Holiday said after Friday's practice.
Bulls coach Fred Hoiberg acknowledged that Portis' apology took place during a team meeting but did not want to go into specific details about his message.
"I'll keep that between the team," Hoiberg said, "as far as exactly what was said in that meeting."
Portis, who has declined to speak to the media for now, practiced Friday for the first time since Tuesday's incident. He was suspended eight games for punching Mirotic.
"It was good to have him back in here," Hoiberg said of Portis. "Obviously everybody's looking forward to getting Niko back in here as well, hopefully soon."
Mirotic, who was not in the building, is expected to miss at least four weeks because of his injuries.
Holiday said Portis' demeanor on the floor hadn't changed.
"Bobby came in today like Bobby," Holiday said. "We're not sure what he's thinking mentally and we can't assume that. ... [But] when he got into practice, he worked hard like he always does, and that's important for our team right now."
Hoiberg echoed Holiday's sentiments.
"His spirit was good," Hoiberg said of Portis. "Right now, our job is to get the guys out there that we have and get them prepared to play different positions than they've been playing. So he didn't get a lot of reps out there today. It was really a shorter, correcting, teaching-type practice.
"We did get up and down a little bit. Bobby did step out there in certain drills, but we've got guys that have played positions that they haven't played the entire preseason, with Paul [Zipser] and with Quincy [Pondexter]. So that's the biggest thing that we have to do right now as far as preparing until we get our guys back is throwing different lineups out there and hopefully getting better with our execution."
With Mirotic and Portis both unavailable, rookie Lauri Markkanen started at power forward in the Bulls' season opener, a 117-100 loss in Toronto. Markkanen scored 17 points and grabbed eight rebounds.
It remains unclear when Mirotic will be on the floor again.
"I've reached out to Niko through text," Hoiberg said. "He's still sore. He's still very sore. But I think every day he'll be getting a little better."