"I can only speak from my own experience, and our experience with the mayor has been incredibly constructive and positive," Perez told ABC News in an interview.
"Michael Bloomberg should not be speaking tonight," Brianna Westbrook, a former Sanders surrogate and Arizona Democratic Party official, tweeted earlier Thursday.
One group of former field staffers suing the mayor sent Perez an open letter calling on him to remove Bloomberg from the DNC program this week.
"I haven't reviewed their lawsuit," Perez said when asked if they had valid legal claims, "because I've focused 100% on this convention and electing Joe Biden."
Perez said the party has "hired many Bloomberg alumni" and interviewed or offered jobs to over 600 former Bloomberg campaign staffers.
"I appreciate what the mayor has done," Perez said. "He kept his word to us when he said, 'I'm in it to win it. If I'm not in it, I will be supporting the Biden campaign and the DNC.' And he has done that. I really appreciate the folks who are on our campaigns right now from his team."
A spokesperson for Bloomberg called the open letter a "distraction," and denied that he had "promised employment through November." (The former staffers claim Bloomberg's hiring representatives made those commitments during the hiring process.)
"Nobody has done more than Mike Bloomberg to help Democrats up and down the ticket," the spokesperson told ABC News in an email. "He's one of the nation's most effective leaders in supporting Democratic candidates and causes such as gun violence prevention and climate change."
"Mike delivered a powerful speech at the Democratic Convention in 2016 against Trump and is looking forward to doing so again," the spokesperson added. "Stunts like these merely serve as distractions from our common goal of defeating Donald Trump and ending his existential threat to America."
Bloomberg, who had said he would keep his campaign offices open through November, decided to instead transfer $18 million to the DNC (and transferred several of his offices to the party) after he left the presidential race following a disappointing Super Tuesday finish.
He has also since agreed to provide health insurance for former staffers through November, amid the pandemic.
While Bloomberg and his aides suggested they would spend heavily -- as much as $1 billion -- to defeat Trump even if he wasn't on the ballot, they have yet to do so. Still, Bloomberg -- who spent roughly $1 billion on his own presidential bid -- signaled earlier this week that he will commit $60 million to help reelect House Democrats.
Hawkfish, a political data and digital firm founded by Bloomberg, continues to work with Democratic-aligned groups ahead of the November election.
Perez, reflecting on the Democratic National Convention this week, said the format of the virtual summit "makes it harder to accommodate everyone," but said the program "has reflected the broad diversity of our party."
He also suggested that some of the new features -- such as the virtual roll call -- could be a "trend of the future," even at subsequent in-person conventions.
"It had such a unifying feel to it," he said. "And I think there's going to be a lot of pressure in the future to replicate models like that."