Michael Takàcs, head of Austria's federal police, said the attempted acts of cyber sabotage were thwarted.
They targeted not only the Eurovision website but also access control systems at the venue.
The perpetrators sought to disrupt, slow down or disable systems, Takàcs said at a press conference on Monday, adding that no details were available on those responsible or their motives.
Interior Minister Gerhard Karner said the goal had been to ensure a safe and peaceful event.
"We succeeded," he said, noting that no serious incidents were reported at live broadcasts, public viewing events or related demonstrations.
Austria's Interior Ministry State Secretary Jörg Leichtfried said authorities closely monitored potential threats from Islamist extremists and violent groups linked to Iran.
Around 3500 Austrian police officers were deployed during the final week of the contest in Vienna, supported by special units from Germany's Bavaria region, officials said.
Domestic security services also monitored social media activity, where Leichtfried said an increase in "polarisation and radicalisation" had been observed.
Eurovision was accompanied by several demonstrations, most of which were directed against Israel's participation.
Shortly before Saturday's final show, in which Bulgaria came out on top, 14 masked pro-Palestinian activists were detained for failing to end their peaceful but unauthorised rally despite police orders.
A total of 16 detentions were made in connection with Eurovision, including a person who attempted to scale a barrier around the venue.
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