ITV has been warned against relying on a "combative dynamic" between presenters, such as Piers Morgan and Susanna Reid on Good Morning Britain, because it risks breaching the broadcasting code.
Ofcom issued the warning after there were more than 1,600 complaints after Morgan used a "racist trope" and mimicked the Chinese language during an episode of the breakfast TV show on January 21.
During a discussion about Peter Phillips, the Queen's grandson and son of the Princess Royal, starring in a TV advert for Chinese state milk, Morgan mimicked the dialect and used the phrase "ching chang".
He also referred to it as "yeng yeng dong dong yong ming ming milk... milk".
When Reid told him: "Taking the mickey out of foreign languages is rather 1970," Morgan replied: "I'm sorry you can take the mickey out of it. It is ching chang chong milk, right?"
Reid replied: "You can't."
As his co-presenter continued to tell him it was inappropriate, Morgan insisted he was mimicking the wording of the advert, rather than the language.
He said: "I can't speak Chinese. I'm trying- I'm trying- I am trying to mimic the wording of that advertisement."
He added: "Sorry, are people now going to be more annoyed at me trying to mimic the Chinese state milk ad than they are about a member of the royal family flogging Chinese state milk?"
Reid replied: "Yes, Piers do you not realise the kind of woke times we're living in?"
ITV later apologised for the incident, saying in a statement: "GMB is known for its lively and robust discussion of the news agenda and recently covered Peter Phillips' appearance in a Chinese milk advertisement.
"The discussion was focused on whether it was appropriate for members of the royal family to endorse products abroad in this manner, and was live and unscripted.
"Piers Morgan's comments, and his mimicking of the Chinese language in the advertisement, was a spontaneous reaction to the advertisement.
"These comments were intended to mock a member of the royal family and were not intended to mock or denigrate Chinese people, their language or accent.
"ITV regrets any offence Piers' comments may unintentionally have caused."
In its assessment and decision not to pursue a full investigation, Ofcom said that during a discussion of this nature, "it was legitimate for Piers Morgan to question Peter Phillips' decision to appear in an advertisement for Chinese state milk and to use satire and ridicule in doing so.
"However, part of Piers Morgan's mockery included three attempts to mimic the Chinese language, including using the phrase 'ching chang'.
"As ITV has itself acknowledged, this phrase is recognised as a racist trope aimed specifically at people of Chinese heritage.
"Our recently published research indicates that audiences have a particular concern about content which is discriminatory.
"In our view, the use of the phrase and variations of it had the potential to be particularly offensive to viewers."
Ofcom also referred to Reid's interjections, saying: "We accepted this was an attempt by Susanna Reid to point out that some viewers would find his imitation offensive.
The regulator added: "Having carefully considered the context within which the comments were broadcast and the action taken by ITV, including discussing these complaints with Piers Morgan and making a public apology, Ofcom concluded overall that this programme did not warrant further investigation under rule 2.3 of the Code.
"We remind ITV that there are compliance risks in relying on a 'combative dynamic' between presenters as a way to provide challenge and context for the broadcast of content which may cause offence.
"This approach can provide significant context, as in this case.
"However, depending on the particular circumstances, this may not always provide sufficient context to comply with the code."