Apple sales have fallen in almost every market across the globe, according to the latest results from the tech giant.
The company said that demand for its smartphones dropped by more than 10% in the first three months of this year, while overall sales fell in every geographic region except for Europe.
Apple said that overall, revenues across the company declined by 4% to $90.8bn (£72.5bn), which was the biggest drop for more than a year.
Nevertheless, the results were not as bad as expected and Apple's share price rose in after-hours trading in New York.
The company said the figures were distorted by Covid-related supply disruptions, which led to unusually strong sales during the same period last year.
It said it expected sales to return to growth in the months ahead, noting upcoming product launches and investments in artificial intelligence (AI).
Overall sales in the critical greater China market dropped by 8%. Mr Cook attempted to reassure investors about the state of the business in the world's second largest economy, noting that iPhone sales were actually up in "mainland" China.
"I maintain a great view of China in the long term," he said.
Competition in that market has been intensifying from local rivals such Huawei.
Gil Luria, senior software analyst at DA Davidson, said companies such as Huawei do well in China because "it is the homegrown brand".
"But in terms of features, functionality and prestige, iPhone still has an advantage over any other handset," he told the BBC's Today programme.
"So any time consumers get the choice and have the resources they’re going to buy an iPhone – that’s not any different in China."
Struggles at the company - which has endured a streak of sales declines for five of the last six quarters - marked a contrast with the wider market.
Globally, smartphone shipments rose 10% in the first three months of the year, expanding after a long lacklustre period, according to research firm Canalys.
Mr Luria said that for Apple, there hasn't been "significant improvements to the handset" since the iPhone 12 was launched almost four years ago "when Apple introduced 5G connectivity which compelled a lot of consumers to upgrade the phone".
He added: "What they’re hoping for now is that they can introduce enough new AI features into the iPhone 16 which will come out later this year in order to finally drive a big iPhone upgrade cycle.”
Apple is also facing legal battles with regulators in the US and Europe over its app store fees.
A separate anti-monopoly lawsuit in the US against Google threatens the lucrative payments Apple receives from the search giant in exchange for making Google the default search engine on Safari, Apple's internet browser.
According to court filings, those payments amounted to about $20bn in 2022, a sum that helped lift Apple profits.
Pre-tax profit for the three months was flat at $28bn and the company announced that it was setting aside $110bn to buy back shares.
Finance chief Luca Maestri said Apple sales were expected to rise in the "low single digits" in the three months to June.
He added that the firm expected double digit growth in its services business, offering more guidance than the company typically provides.
Looking ahead, Angelo Zino, senior equity analyst at CFRA Research, said: "China is holding up better than expected and there are a host of upcoming events/catalysts on the horizon that could improve investor sentiment."
