Zimbabwe's foreign affairs minister has summoned the United States ambassador to explain recent critical remarks about the Zimbabwe government.
Mr Dell blamed food shortages on corruption
Minister Simbarashe Mumbengegwi said he had summoned Ambassador Christopher Dell to convey to him the government's "extreme displeasure" at recent events.
Last week, Mr Dell said the Zimbabwe government was responsible for the country's current food crisis.
Democracy activists in Zimbabwe remain in jail after Tuesday's clampdown.
"I have just summoned the ambassador of the United States, Mr Christopher Dell, to convey to him the extreme displeasure on the part of the government of Zimbabwe relating to the ambassador's recent activities here in Harare as well as in Mutare," Mr Mumbengegwi told reporters.
During a lecture in the eastern Zimbabwean city of Mutare last week, Mr Dell said corruption was to blame for food shortages. The government blames Zimbabwe's economic problems on sanctions.
Last month the ambassador was briefly detained after walking into a security zone near the presidential residence in Harare.
Zimbabwe state media on Monday said Mr Dell risked expulsion from Zimbabwe, and on Tuesday quoted President Robert Mugabe as saying the ambassador could "go to hell".
Relations between the US and Zimbabwe have soured in recent years, with Washington accusing Mr Mugabe's government of rigging elections and abusing human rights.
The UN says up to three million people in Zimbabwe need food aid, and has criticised Zimbabwe for refusing aid.
On Monday night and Tuesday, police detained activists from the pro-democracy National Constitutional Assembly and the Zimbabwe Congress of Trade Unions in connection with demonstrations.
On Wednesday the NCA said it was "extremely disturbed" by the continued detention of its chairman, Lovemore Madhuku, who the NCA says has been transferred from Harare Central Police Station to the "infamous" Stodart Police Station in Mbare township.
The NCA also says Misheck Shoko, mayor of Chitungwiza, a dormitory town near the capital, is being held at Mbare police station, and three other NCA members were arrested up in Chitungwiza in Tuesday.
At least 80 trade unionists, including top ZCTU officials, were arrested on Tuesday.