WASHINGTON — Hundreds of protesters gathered outside the State Department on Monday, the start of a summit meeting here of more than 40 African heads of state, to denounce some of the leaders as “torturers” and “killers.”

The protesters, who were mostly from Ethiopia and the Democratic Republic of Congo, said they were angry that the White House was looking to enhance economic ties with repressive governments. “Stop financing dictators,” the crowd chanted. “President Obama, shame on you.”

Obang Metho, director of the Solidarity Movement for a New Ethiopia, referenced Mr. Obama’s message to African leaders during his 2009 trip. “Africa doesn’t need strongmen. It needs strong institutions,” Mr. Obama said at the time.

“Now he is sitting with strongmen,” Mr. Metho said. “Where are the strong institutions?”

On Tuesday, Mr. Obama will host the leaders at the White House for dinner and will then take part in a series of meetings on Wednesday, mostly focused on increasing United States investment in Africa and promoting peace and stability on the continent. As the summit meeting began, the White House also announced that it would institute new programs and foreign assistance aimed at promoting gender equality in Africa.

The sessions on Monday began with a forum on supporting civil society, and the leaders heard from Vice President Joseph R. Biden Jr. “It’s not possible to succeed for your people unless they have a chance to shape the policies of their government, identify problems and root out injustices and find ways for groups to resolve their differences peacefully,” Mr. Biden said.

Secretary of State John Kerry also addressed the leaders and met one-on-one with Joseph Kabila, president of the Democratic Republic of Congo. When Mr. Kerry was in Congo earlier this year, he urged Mr. Kabila to step down after his current term, as Congo’s constitution requires. “Large majorities of Africans support free, accessible and fair elections and limiting their presidents to two terms in office,” Mr. Kerry said Monday.

Protesters outside the State Department said they hoped that the Obama administration would continue to press Mr. Kabila on the term limit.

“Obama must give a clear message that the president doesn’t change the constitution to stay in power,” said Constant Mbala, who moved to the United States from Congo 15 years ago.

The streets between the White House and the State Department were largely absent of traffic on Monday, as Washington residents had been warned of street closings and the likelihood of traffic congestion because of heightened security and the dozens of motorcades that would be driving around town.

African trade officials also convened with their American counterparts on Monday for annual meetings on the African Growth and Opportunity Act. The program, known as AGOA, lowers the tariffs on certain African goods imported to the United States, while countries in Africa are not obligated to lower the duties on any United States goods. It has been credited with helping to diversify and improve other sectors of the African economy, but oil still accounts for three-quarters of the African goods imported by the United States duty free.

The program requires reauthorization by Congress next year, and one of the questions is whether South Africa should continue to benefit from preferential trade status, as some say that its current economic growth means that it should extend a preferential tariff system to some United States goods as well. But while speaking at a luncheon hosted by the National Press Club on Monday, President Jacob Zuma of South Africa dismissed this idea.

“We look forward to a seamless, unconditional and long-term renewal of AGOA...."