The Czech exchanged a brief word with Sakkari at the net before approaching Mrozinska with an outstretched hand before withdrawing it and repeatedly smashing the chair with her racquet.
Pliskova's twin sister Kristyna, who also ranks in the world's top 100, slammed Mrozinska on social media.
"The worst i have ever seen @wta and i hope this lady Marta Mrozinska will never ever judge any match of me or Karolina again #blacklistforever," the 26-year-old wrote on Twitter.
Earlier in the day, top seed Simona Halep produced a ruthless display to see off Japan's Naomi Osaka 6-1 6-0.
The Romanian was forced to save four break points in her opening service game but went on to claim 12 consecutive games to avenge her Indian Wells loss to eventual champion Osaka in March.
The 20-year-old Osaka failed to convert any of her six break points before conceding the match in just under an hour.
"I just tried to build my points, to build a little bit of space and open the court, and tried to make winners," Halep said.
"It's tough to make winners on this court, for me, but it's good when I can build the point. I just want to play like today."
Halep will next meet American Madison Keys, who clinched a 7-6(2) 7-6(0) win over Croatian qualifier Donna Vekic.
World number two Caroline Wozniacki began her campaign with a comfortable 6-1 6-4 victory over Belgian Alison van Uytvanck.
The 27-year-old Dane, chasing her first claycourt title since 2011, will face 15th seed Anastasija Sevastova for a place in the quarter-finals.
A decade after they last met in Rome, Maria Sharapova once again did enough to secure a victory over Dominika Cibulkova in three sets.
Former world number one Sharapova struck 41 winners as she rallied back from a set down to edge her Slovakian opponent 3-6 6-4 6-2 in a thrilling 2-1/2 hour contest.
The 31-year-old Russian will next face Australia's Daria Gavrilova for a place in the quarter-finals.
Gavrilova recovered from 4-0 down in the third set to beat world number three Muguruza 5-7 6-2 7-6(6) in just over three hours.
The victory means the 24-year-old Gavrilova recorded her first top 10 victory of the year, and her first back-to-back match wins since Acapulco in February.
(Reporting by Hardik Vyas in Bengaluru, editing by Pritha Sarkar / Ian Ransom)
