A senior Sinn Féin member, Michael Agnew, has been targeted in a pipe-bomb attack at his home in Ballymena, County Antrim.
British army bomb disposal experts defused the device under his vehicle.
A second device was discovered under the car of another nationalist living in the area.
Mr Agnew said he was in no doubt that unionist paramilitaries were responsible.
“Political leaders should speak out against the intimidation of political activists,” said Mr Adams.
“These attacks . . . will not deter Sinn Féin from defending the Agreement or in delivering the agenda for change required to transform society on this island,” he added.
The attacks followed a previous double bomb attack on another republican in Ballymena last month.
The 54-year-old said the device could have easily killed another man who is the regular driver of the van.
“The PSNI told me it was a viable device,” he said.
“It was an eight-inch pipe bomb with a battery and timing device attached to it.
“I saw it wasn’t attached to the van so I drove it away from the device.
“If someone had driven over it I have no doubt they would have been seriously injured or even killed.”
“There is an ongoing escalation of attacks on Sinn Féin members and republicans in the Ballymena area,” he said.
“Loyalists are intent on trying to intimidate and censor republicans living in the area.
“The second man whose home was attacked this morning isn’t even a member of Sinn Féin.
“His family use the car and if his wife had got into the vehicle she could have been killed.”
* A Catholic mother and son have fled their County Derry home after unionist intimidation.
The woman and her 16-year-old son, who did not want to be named, left their home in Coleraine following a number of incidents.
The family moved out of the property last Monday, after a threatening notice was taped to her back door.
“These threats began six weeks ago when she got a letter declaring that ‘fenian scum’ was not welcome in the estate. Stones were then thrown at the house and unionist youths began congregating outside playing flutes.
* Nationalist politicians have condemned a petrol bomb attack at the home of a pensioner in south Belfast and have made investigations in an attempt to prevent a recurrence.
It is not clear who carried out the attack in the unionist Donegall Pass area, but there were claims that nationalist youths were involved.