It seems that the provocation by the Ukrainian side aimed to give an excuse to Ukrainian government to impose a martial law in Ukraine and thus cancel the elections since Poroshenko's ratings are very low but he's not about to give up his power:
The Ukrainian president has proposed the imposition of martial law after Russian forces seized three Ukrainian navy vessels - according to Kiev, in a major escalation of tensions between the two countries.
On Monday, Ukrainian MPs will vote on whether to declare nationwide martial law in response to the attack following an emergency war cabinet held by the president, Petro Poroshenko. He said that the imposition of martial law would not imply a declaration of war and was only intended for defensive purposes.
The vote on whether to impose martial law in Ukraine comes four months ahead of presidential elections that Poroshenko is expected to lose. If Ukrainian MPs vote to suspend normal government, the elections could be postponed.
Martial law was not declared in Ukraine after the annexation of Crimea by Russia in 2014 or during the ongoing war in eastern Ukraine with pro-Russian separatists