Tama Langkun, an activist from the Indonesia Corruption Watch (ICW), who had investigated several top police generals and their alleged bank accounts, has been hospitalised after the assault early on Thursday morning.
"Whatever the challenges, obstacles and threats that are being experienced by all who combat corruption, this big mission has to continue," Yudhoyono told reporters after visiting Langkun.
"The show must go on. We should not be afraid of any threats and acts of violence," Yudhoyono said, adding that everyone who shared the goal of eradicating graft should support each other.
Langkun was hit on the head while on his way home after watching a World Cup match. He was attacked by four people on two motorcycles who are still at large.
The assault came two days after firebombs were thrown at the Jakarta office of a respected news weekly which published an article this month alleging top police generals have millions of dollars hidden in their bank accounts.
Yudhoyono has had ordered law enforcers to find out who was behind the attacks and the attackers' motives.
Civil society groups and anti-corruption activists, who accuse the government of failing to protect whistleblowers or control rampant graft in the police force, condemned the acts of violence.
Police last week threatened to sue the news weekly, Tempo, over a report that accused senior police generals of accumulating millions of dollars in bank accounts from illegal activities.
The threat was not related to the corruption allegations, but to cover artwork depicting a police officer with piggy banks, as pigs are considered offensive in mainly Muslim Indonesia.
The Indonesian police force is seen as one of the most corrupt institutions in one of the most corrupt countries in the world.
Source: AFP Asian Edition