The PSNI said a “military style hand grenade” was thrown at police in east Belfast on Friday night.
Police officers were responding to reports from local residents of anti-social behaviour in the Short Strand area when the device was thrown at about 10.15pm in the vicinity of Pottingers Quay.
The object did not detonate and there were no injuries.
A number of homes were evacuated amid the security alert.
Dissident republicans are suspected of being responsible.
The PSNI said late on Saturday afternoon the Short Strand had reopened following an overnight security operation.
Supt Bobby Singleton of Belfast City Policing District earlier said those who carried out this attack “showed a total disregard for the safety of the local community and worryingly for the second time in as many days young people who were in the vicinity” at the time of the attack.
‘Sheer good fortune’
“It is only by sheer good fortune that we do not have a fatality on our hands as this attack occurred in a built up residential area,” he added.
“This is the second attempt by terrorists to kill people in Belfast in 48 hours. Thankfully, on both occasions, they failed but I would appeal to people to remain vigilant and appeal to everyone in the community to continue to work with police by providing information to us so we can keep everyone safe.”
The incident on Friday came the day after a suspected booby trap bomb was found on a street in north Belfast. The viable explosive device was apparently kicked by a young boy while it lay on the ground in Linden Gardens, off the Cliftonville Road.
Detectives are investigating whether the bomb had fallen off a car belonging to a man with a connection to the armed forces. Dissidents were again suspected.
‘Crude but viable’
Police are also appealing for information after a “crude but viable explosive device” was discovered in the Elm Park Road area of Killylea, Co Armagh on Friday afternoon.
Meanwhile, the security alert in Omagh following the discovery of a suspicious object close to Strule Arts Centre has now ended. The PSNI said an army bomb disposal unit carried out a controlled explosion on the object and "nothing untoward" was found.
A PSNI spokesman said High Street, George’s Street and Bridge Street in the Co Tyrone town were closed to traffic and a number of businesses evacuated.
Members of the public were advised to avoid the area of Omagh town centre while the alert continues.
Security alert
There was a security alert at the Strule Arts Centre last week after dissident republicans targeted the venue ahead of a PSNI recruitment event.
Nothing untoward was found there or during a similar alert at a Belfast Metropolitan College campus.
However, a bomb was made safe in the grounds of the Waterfoot Hotel in Derry, another venue due to stage a police familiarisation session.
The Derry event was subsequently cancelled by the hotels owners amid concerns for staff safety.
The information session, which comes after the PSNI advertised for 100 new recruits, is due to take place at St Columb’s Park House on the Limavady Road in Derry on Saturday.