He also pointed to the impact of the company's response to the April arrest of two black men in a Philadelphia store, including the May 29 afternoon closure of 8,000 USA stores for anti-racial bias training.
Several analysts downgraded their ratings and cut their 12-month targets on Starbucks' stock, after the company on Tuesday forecast sales growth at established restaurants of just 1 percent in the third quarter, below Wall Street's expectations of 3 percent.
Starbucks Corp (SBUX.O) shares fell more than 8 percent on Wednesday after a disappointing sales forecast from the US coffee chain prompted Wall Street analysts to question the sustainability of its growth at home and in its next biggest market, China.
"Our recent performance dos not reflect the potential of our exceptional brand and is not acceptable", he said.
Starbucks says it will also add more teas to its menu and plans on "capitalizing on health and wellness trends" Bloomberg notes. The overall number of stores will continue to increase, but that growth will be focused.
Starbucks fans may be in for some bad news.
Melania Trump 'hates' to see children separated from families at U.S. border
I don't think you have to justify it", former White House chief strategist Steve Bannon said Sunday on ABC's "This Week". The government pays more than $1 billion a year to care for unaccompanied immigrant children, Sessions has said.
With Wednesday's decline, Starbucks' shares were on track to enter negative territory for 2018 - a year in which co-founder Howard Schultz stepped down as executive chairman and the company found itself at the center of an embarrassing racial profiling incident. "That becomes an area of concern for Starbucks".
The company faced a backlash earlier this year when two black men were arrested at one of the company's Philadelphia locations when staff called the police.
Johnson said Starbucks has not reached saturation point in the USA, but it will be more strategic about where it puts new stores, focusing on underpenetrated markets in "Middle America".
According to Andy Sookram, who tracks the company for S&P Global, the issue is that sales at Starbucks locations open at least a year - an industry measure that takes a chain's unit growth into account - aren't as brisk as they historically have been.
The chain is also relying on its digital initiatives to contribute between 1 and 2 percent to comparable sales next fiscal year.