The London-based human rights watchdog also said widespread human rights abuses during the campaign was a major concern.
The group was worried candidates who did not have the backing of the Liberation Tigers of Tamil Eelam (LTTE) could become targets for assassination.
The LTTE is not contesting the elections called by President Chandrika Kumaratunga on 2 April, but announced it would back a moderate group, the Tamil National Alliance (TNA), which is seen as a Tigers proxy.
Diplomats and analysts say the TNA, which had 15 seats in the earlier parliament, can bag a sizeable number out of the 31 seats in the Tamil-dominated northeast.
With the majority Sinhalese community split down the middle between the parties of Kumaratunga and her arch rival Prime Minister Ranil Wickremesinghe, the Tamils could hold the balance of power.
"We are particularly concerned that candidates and supporters of (minority) Tamil political parties not allied to the TNA - which the LTTE is backing in the elections - may become targets for assassination"
Human rights watchdog
"We are particularly concerned that candidates and supporters of (minority) Tamil political parties not allied to the TNA - which the LTTE is backing in the elections - may become targets for assassination," Amnesty said in a statement.
It also called for the freedom of movement for political activists in areas held by the Tamil Tigers.
It said the LTTE was suspected to be behind the assassinations and attempted killings of more than 50 members of Tamil political groups and several Muslim civilians since a ceasefire took effect in February 2002.
"We are also appealing to all parties contesting the elections to put human rights at the heart of their agenda," Amnesty said.
It called on parties to make clear their commitment to undertaking reforms to ensure protection and promotion of human rights, ending impunity and ratifying international rights and humanitarian standards.
"The potential for serious and widespread human rights abuses during the campaigning period is now a major concern," Amnesty said.
It said there were already reports of more than 100 election-related incidents of violence, including injuries to 40 party activists in clashes in southern and north-central regions after the close of nominations on Tuesday.
Four people were also allegedly abducted by the LTTE in the east of the island since the elections were announced, Amnesty said.
The campaign for the December 2001 parliamentary election was marred by violence that left at least 41 people dead and more than 700 wounded.