The US is working to lift a 14-year-old embargo on selling weapons to Haiti in order to help police cut rising crime and unrest before elections this year.
Haitian police have been ill-equipped to combat gun crime
Washington's ambassador to Haiti, James Foley, said guns were urgently needed to help police guarantee security.
Haiti's cabinet chief, Michel Brunache, said a US marine deployment could help restore order in time for the polls.
Some 700 people have died in less than a year in Haiti, in a crime wave blamed on politically-aligned gangs.
Elections due to be held in the Caribbean nation this autumn will be the first since an armed uprising forced former President Jean-Bertrand Aristide into exile last year.
The US has said slum gangs loyal to the former leader are behind much of the crime and unrest in the country.
Human rights groups have accused the police of summary executions of Aristide supporters - a charge the authorities deny.
At a ceremony in the Haitian capital, Port-au-Prince, Ambassador Foley said "guns are an extremely important element for police to guarantee security".
An estimated $2.6m (£1.4m) worth of security equipment - including trucks, tactical vehicles and motorcycles - were donated to the police during the ceremony.
The US state department and Congress are also considering plans to train Haitian police.
The US has acknowledged that it gave Haiti's police some 2,600 used firearms last year, making an exception to its own embargo.
The top US diplomat responsible for the western hemisphere, Roger Noriega, visited Haiti on Wednesday for talks with the interim Prime Minister Gerard Latortue.
He is believed to have discussed measures to stabilise Haiti before the polls.
On Tuesday, Mr Latortue asked the United Nations for more French-speaking peacekeeping troops to be sent to Haiti.
About 7,400 UN peacekeeping troops are already in Haiti and US Secretary of State Condoleezza Rice said on Saturday that more might now be sent.