US President George W Bush on Wednesday spoke to Indian Prime Minister Manmohan Singh and Pakistan President Asif Ali Zardari and all the three leaders agreed to avoid any action that would "raise tensions" in the region. Bush in his telephonic conversation with Zardari in the backdrop of Indo-Pak tension over suspected involvement of Pakistan-based terror outfits in the Mumbai carnage urged Islamabad's cooperation in the on-going probe. Bush "called Indian prime minister (Manmohan) Singh of India and separately president (Asif Ali) Zardari of Pakistan. President Bush urged both ... to cooperate with each other in the Mumbai attack investigation as well as on counter-terrorism in general," White House spokesman Gordon Johndroe said. Bush spoke from his ranch in Crawford in Texas. "All three leaders from the United States, India and Pakistan agreed that no one wanted to take any steps that unnecessarily raise tensions," Johndroe emphasised. "... the calls he(Bush) had with both Prime Minister Singh and, separately, with President Zardari were encouraging the sides to cooperate, not only on the Mumbai investigation, but also on counterterrorism in general. And I'll leave it at that," Johndroe said. In Islamabad, a brief statement issued by the presidency said Zardari assured Bush that Pakistan will not allow its territory to be used by "non-state actors" for launching attacks on other countries. Bush's phone conversation with Zardari was the latest in a flurry of contacts between top US and American officials in the wake of the Mumbai terror attacks, which sparked tensions with India.