Kelly was referring to a peace proposal advanced by Oscar Arias, the Costa Rican president, under which Zelaya would be reinstated as the Honduran president until elections are held in November.
In return, Zelaya would have to abandon plans to hold a referendum on changes to the constitution, the issue which was opposed by the Honduran supreme court, congress and army and which ultimately led to him being forced from the presidential palace on June 28.
Foreign ministers from members of the Organisation of American States (OAS) are in Tegucigalpa to try to convince Roberto Micheletti, who leads the military-backed interim government, to accept the terms of the San Jose Accord.
Human Rights Watch (HRW), a New-York based organisation, said on Tuesday that the US government must impose fresh sanctions against the Honduran interim government if its does not accept the terms of the accord on offer.
"If the OAS delegation is unable this week to persuade Honduras' de facto government to allow Zelaya's return to the presidency, the only option left will be for the international community to ratchet up the pressure," Jose Miguel Vivanco, the HRW director for the Americas, said.
"The US government, in particular, could play a key role through the use of carefully targeted sanctions," he said.
Washington has so far put about $18m in mostly military and development aid to the interim government on hold since Zelaya was overthrown.
But the Obama administration has argued that placing further sanctions on the country runs the risk of adversely affecting the economy, to the detriment of the population.
To avoid harming the general population of Honduras, the US could cancel the travel visas of members of the interim government and block them from using US banks, Vivanco suggested.