HARARE, Zimbabwe (CNN) -- Police twice stopped a group of diplomats Tuesday -- including the U.S. ambassador to Zimbabwe -- asking questions about journalists accompanying them and threatening violence, according to an eyewitness.
Morgan Tsvangirai alleges his opposition supporters have been targeted by Zimbabwe security forces.
In the first incident, Ambassador James McGee and a group of journalists had just toured a hospital that is treating victims of recent post-election violence when seven armed police closed the gates to the facility and stopped them.
They wanted to "ask him questions" about photos the group had taken, said Paul Engelstad, a spokesman for the U.S. Embassy in Zimbabwe. The U.S. State Department called the incidents "harassment."
The incident occurred in the village of Mvurwi, a small mining town about 100 km (62 miles) north of Harare. Also in the group were the ambassadors of the European Union, the United Kingdom and Japan, as well as the deputy ambassador of the Netherlands.
McGee refused to answer the questions, personally opened the gates and motioned to his convoy to proceed. They left without incident. The police "never said they were going to arrest him," Engelstad said. 
Watch video of the disrupted trip »
Police also wanted a photographer to delete footage he had taken of the altercation, the eyewitness said. McGee refused that as well.
The ambassador later described the incident as a "minor misunderstanding."
After leaving Mvurwi, the diplomats traveled to the Chiweshe and Glendale areas on their way to Harare. Police also stopped them for about an hour on that route.
They were asked to drive to the nearest police station to produce a diplomatic note, but the diplomats refused, saying they could do that at the scene.
Andrew Sturr, a USAID official, was asked the purpose of the visit and said that it was to see the victims of violence. A Zimbabwean Central Intelligence Organization official apparently replied, "We are now going to beat you, too."
Police wanted to know the identities of the journalists and photographers who had accompanied the diplomats to Mvurwi and Chiweshe, but McGee expressed ignorance. The incident ended and a police car escorted the entourage into Harare.
"It was just a way of trying to make a statement that they can control us," Engelstad said.
"They did not want us to have first-hand information of the level of brutality taking place in the countryside ... we have seen it, and people feel threatened in their own country."
U.S. State Department spokesman Sean McCormack said: "If on two occasions you're held up for nearly two hours and questioned about what you're doing by security officials, then yes, that's harassment, sure."
He added: "If you have foreign diplomats accredited to Zimbabwe who are facing this kind of treatment, you can only imagine for Zimbabwean citizens what life is like if they make an effort to speak up to voice their opinions."
Presidential and parliamentary elections were held in the country on March 29, and it has been wracked by violence since.
Last week, Zimbabwe's main opposition party, the Movement for Democratic Change (MDC), said 25 of its supporters have been killed, and church groups reported the deaths of eight people at the hands of militias in an apparent crackdown on the opposition and its supporters.
Supporters of the MDC say their candidate, Morgan Tsvangirai, won the election outright. But Zimbabwe's election commission says that, while Tsvangirai got more votes than President Robert Mugabe, he did not get the necessary 50 percent plus one vote to avoid a runoff election.
CNN's Carolina Sanchez contributed to this report
All About Zimbabwe • Robert Mugabe • Morgan Tsvangirai • Thabo Mbeki
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