While Albanese said it was too early to understand the motive behind what had happened, he did say the political temperature had been rising in Australia.
His Home Affairs Minister Tony Burke backed up that statement with figures showing that reports of threatening or harassing behaviour towards politicians had risen from 951 to 1,067 in the past year.
Haines was hit by a white Toyota Landcruiser at 15:35 (04:35 GMT) outside her office on Murphy Street in Wangaratta, police say.
The town, which has a population of around 30,000, is a few hours north-east of Melbourne.
A witness told Australian broadcaster ABC they had heard a bang and seen a woman pinned between two cars, external.
Haines was initially taken to a hospital in Wangaratta but later moved to Melbourne by helicopter.
After being subdued and detained by the passersby, the suspect was arrested by police.
Announcing that counter terror police were involved in the investigation, the prime minister said: “This wasn’t an accident. There was a deliberate act, it would appear.”
In a statement, Victoria Police said: “At this stage, police are investigating as to whether this was an intentional act.
“It is not known yet if the parties are known to each other… The investigation remains ongoing.”