The blast, which occurred around 17:20 GMT on Thursday, was followed by a second explosion, police and ISAF said.
One rocket landed inside the Kabul Multinational Brigade (KMB) base on the Jalalabad road 12km east of central Kabul.
There was no immediate report of injuries or damage from the attack.
ISAF spokeswoman Major Sarah Wood said the explosion occurred in a corner of the base used for shipping containers and was likely to have caused some damage.
"Our immediate priority is to look after our people and then cordon the area," she said.
One policeman said the rocket appeared to have been fired from the nearby Ko-i-Safi mountain.
A second explosion was heard at 18:30 GMT but it was not immediately clear whether it was another rocket attack.
"We're just investigating that," Major Wood said.
There were no immediate claims of responsibility but other attacks on foriegn forces have been blamed on Taliban or fighters loyal to former prime minister Gulbuddin Hekmatyar.
Afghan President Hamid Karzai
wants peacekeepers to operate
outside of Kabul
The KMB base is the main base for the 5500-strong international peacekeeping force which is helping with security in the Afghan capital.
Four German peacekeepers were killed in a car bomb attack on 7 June on the Jalalabad road near the base.
The latest incident was the first rocket attack on ISAF since a 30 March rocket attack on the force's headquarters.
Two rockets hit the headquarters in that attack, writing off two vehicles and damaging a building but there were no casualties.
NATO took over command of the multinational force last month in the alliance's first operation outside its traditional European area of operations.
Canada is the lead nation for the Kabul Multinational Brigade, providing 1900 troops for ISAF.
There are three battle groups under the brigade, headed by the Canadians, French and Germans.