Eamon Gilmore admitted the government was concerned about the threat posed by dissident republicans and international terrorists.
However, he said he is confident both visits will be successful.
Mr Gilmore said the Irish police had "considerable experience" dealing with security teams from Britain and the US.
The PSNI has confirmed it will be supplying equipment to the Garda for the royal visit, but would not specify what type.
It said no officers would be travelling south of the border.
Last month members of the Real IRA declared their opposition to the Queen's first visit to the Irish Republic on 17 May.
At a rally in Londonderry they said: "The Queen of England is wanted for war crimes in Ireland and is not wanted on Irish soil."
Mr Gilmore said the government is concerned about the threat.
"Clearly the murder of Ronan Kerr was a stark reminder to us of what a small group of people can do," he told RTE radio.
"We've seen every menacing threats coming from these groups.
"These are obviously taken on board by the government and gardai (Irish police) in making the security arrangements for the upcoming visits and ensuring that none of these group's succeed in carrying out an act that will kill or maim innocent people in this country.
"We are confident that will be done. There is considerable experience for putting in place security arrangements for visits like these."
Part of the arrangements will involve two PSNI water cannons, which have been borrowed by Irish police.
Mr Gilmore said he was also aware of the threat posed by international terrorists following the death of Osama Bin Laden.
"The security arrangements would be very tight and comprehensive in any event and the gardai are making sure that everything is in place and the Irish people will be able to give the traditional welcome to both Queen Elizabeth and President Obama."
Security arrangements for the visits of Queen Elizabeth and US President Barack Obama to Ireland are "very strong", the Irish foreign minister has said.