* Israel says will crack down again on Gaza rocket fire
* Says Hamas probably not to blame but must prevent attacks
* Hamas accuses Israel of stoking tensions
By Crispian Balmer
JERUSALEM, Jan 16 (Reuters) - The Islamist Hamas movement is probably not responsible for a recent upsurge in rocket fire out of Gaza where it rules, but will be made to suffer if the salvoes continue, a senior Israeli military official said.
The official, who declined to be named, said Hamas should intervene to squash the violence, which he blamed on smaller militant groups backed by Iran.
"Hamas is trying to do its best to prevent the launches, but it can and must do more," said the top officer.
Hamas accused Israel on Thursday of exacerbating tensions and said it bore full responsibility for the renewed troubles.
After months of unusual quiet along the fence that separates southern Israel from the Gaza Strip, some 20 missile launches have been detected in the last month, with five fired towards the Israeli city of Ashkelon overnight.
Israel's Iron Dome missile defence system knocked out all five projectiles and the military responded with a series of strikes across Gaza, reviving memories of 2011 and 2012, when such tit-for-tat firing became the norm.
Israel waged a massive air assault on the territory in November 2012, reaching a ceasefire deal with Hamas after eight days of conflict that introduced a prolonged period of calm.
"Both sides understand that we will not return to the days prior to the 2012 operation," said the senior official. "We won't go back to a situation where three or four times a week the red alarm sounds in southern Israeli towns."
Israel captured Gaza in a 1967 war but pulled settlers and soldiers out in 2005. Hamas seized control of the coastal enclave two years later, ousting the Fatah faction of Western-backed Palestinian President Mahmoud Abbas.
Hamas, whose charter calls for the destruction of Israel, has clashed repeatedly with the Jewish state over the years. However, 14 months ago, it accepted a ceasefire deal brokered by Egypt, which at that time was governed by its close ally, the Muslim Brotherhood.
The Brotherhood were ousted from power last July, and the new rulers, backed by the Egyptian military, have since applied huge pressure on Hamas, destroying many of the border-smuggling tunnels that were an economic lifeline for Gaza.
Despite that, the Israeli official said Hamas had continued to try to keep order, preventing smaller radical groups, such as Islamic Jihad, from unleashing their own arsenal of rockets.
He acknowledged that this was a difficult task.
He said some militants fired rockets from locations next to their homes, making them hard to stop, and speculated that the smaller groups were receiving thousands of dollars from Iran for every successful missile launched.
"However, Hamas has proven its ability to prevent terror attacks out of Gaza, so we can demand that they act like a ruler and maintain order," he said.
The United Nations Office for the Coordination of Humanitarian Affairs says 16 Palestinians have been killed by Israeli forces since the end of the 2012 conflict. Over the same period, one Israeli civilian, who was working on the border fence, was shot dead by a Palestinian sniper.
Hamas rejected any blame for the increased tensions. "The (Israeli) occupation is fully responsible for the escalation and aims to create a state of tension continuously," Hamas spokesman Sami Abu Zuhri said.