The attack destroyed a home in central Israel, wounding seven people and prompting Prime Minister Benjamin Netanyahu to cut short a trip to Washington.
Saturday marks the first anniversary of Palestinian protests and clashes along the Gaza Strip's border with Israel. It said a 50-year-old woman was moderately wounded and the others, including an infant, were slightly injured.
In retaliation, Israel hit 100 Hamas targets throughout Gaza. The rocket wounded six members of the home it struck and a 12-year-old neighbour.
On Monday night, a barrage of rockets were fired from the Gaza Strip toward Israel in response to the strikes, causing air raid sirens to ring out in southern Israel.
The reports were a sign Israel was seeking to calm tensions.
In Beirut, the powerful Lebanese militant group Hezbollah said its leader, HassanNasrallah, met Monday with a Hamas delegation led by top official SalehArouri.
Israel shut down its main crossings into Gaza and imposed restrictions on fishing off the Gaza coast. The Israel Defense Forces responded by immediately calling up "thousands" of reserves and mobilizing two armor and infantry brigades.
Monday's incident follows another rare one on March 14 in which two rockets were fired from Gaza towards Tel Aviv.
An Israeli Apache helicopter releases flares as it flies over the Gaza Strip
Ashraf al-Qudrah, spokesperson for Gaza's health ministry, said hospitals and medical points across the strip are ready and on high alert.
Israel's military said they were launched by Hamas, but later there were Israeli media reports that the army's preliminary assessment was that they had been fired by mistake during maintenance work. In a statement, Hamas called for an end to the crackdown.
While Hamas insisted that it had nothing to do with the attack (even though it is supposed to be exercising control over Gaza), the reality is that the terror group believes it can make Netanyahu look bad ahead of the April 9 election, thereby providing a boost to his political rivals.
Israel holds Hamas responsible for all attacks from Gaza, controlled by the Islamist group since 2007.
A firefighter inspects the damage to a house hit by a rocket in Mishmeret, central Israel.
Israel blamed those rocket launches on Hamas, though a security official later said the salvo had been set off by accident. Witnesses reported seeing Hamas evacuating its personnel from government premises.
Hamas also announced that its Gaza chief, Yehiya Sinwar, had canceled a scheduled public speech.
Tel Aviv, Israel's commercial capital, and outlying communities last came under such an attack during the 2014 war with Hamas.