The IDF Spokesperson's Unit said the shells were fired in response to an explosive device planted near the border fence on Saturday evening and hidden in a cutting tool.
The explosive charge exploded as it was being neutralized by a robot. There were no reports of injuries among the IDF forces. The attacked observation post overlooks the area where the device was planted and detonated.
An Islamic Jihad source said following the strike, "We know how to respond to this dangerous Israeli escalation, and we have a right to do so."
On Saturday night, the Israeli army struck targets in a Hamas military complex in retaliation to a Palestinian infiltration into Israel earlier Saturday.
Repeated attempts to damage Israeli security infrastructures near the border under cover of protests organized by Hamas may have also served as backdrop for Saturday night's strike.
The IDF Spokesperson's Unit said in a statement that it "gravely considers continued daily attempts by the Hamas terror group to damage security infrastructures in Israel, while threatening the safety of both soldiers and civilians, and is determined to continuing to defend Israel's citizens."
The army then added its usual refrain, that "Hamas was solely responsible for all goings-on in the Gaza Strip and will face the ramifications of the terroristic activities carried out from Gaza against Israel's citizens and its sovereignty."
The infiltration incident mentioned in the IDF's comment took place earlier Saturday, when four Palestinians crossed the security fence in the southern Gaza Strip and infiltrated Israeli territory, where they lit a Molotov cocktail as part of the "March of Return" protests.
An IDF force that spotted them arrived and fired warning shots. The IDF initially reported that the suspects burned a tire on Israeli land, but later recanted the claim.
Apart from the incendiary bottle, it was reported the suspects left a tent in the field bearing the writing, "March of Return. Returning to the lands of Palestine." It was further communicated the entire incident lasted less than a minute.
Several days ago, Israeli jets attacked a Hamas terror tunnel in the northern strip. Two additional targets belonging to the Gaza-ruling terror group's naval force were also hit.
The IDF Spokesperson's Unit said the strike came in retaliation to an infiltration by Gazans into Israel the previous day, and in light of "continued attempts to fly drones and kites into Israel for the purposes of terrorism and arson."