Leaders of the nine groups in Parliament met with cabinet members on Wednesday to discuss internal security.
According to Yle's sources, the meeting was aimed at calming the situation following last month's stabbings in Turku and other recent incidents.
After the meeting, they issued a joint statement condemning terrorism, violence and hate speech.
It also called for a "peaceful, fact-based, respectful discussion".
The statement was signed by the chairs of seven parties and Finns Party representative Laura Huhtasaari, as well as Sampo Terho, chair of the Blue Reform association, which split off from the Finns Party in June. Finns Party chair Jussi Halla-aho, an MEP in Brussels, did not attend.
The talks were held at the prime minister's official residence, Kesäranta, in Helsinki's Meilahti district. Police and Interior Ministry officials are said to have briefed the party leaders on the progress of the investigation.
The debate over issues such as the terror threat and deportations of rejected asylum seekers has become more heated since the August 18 attack by a young Moroccan man, which left two people dead and eight injured.
Risikko concerned about inflamed tensions
On Tuesday Interior Minister Paula Risikko told Yle she feared that the debate and the way in which situations have become inflamed may impact Finland's societal peace and heighten tensions between Finns.
That same day, there were clashes between police and demonstrators trying to prevent the deportation of an Afghan family in Jyväskylä, and a separate protest by asylum seekers in the northern town of Tornio.
On Monday party leaders met with President Sauli Niinistö to discuss foreign and security policies, including internal security.
Sep. 8: Corrected to say that Huhtasaari represented the Finns Party.