A generic search is presented for a heavy particle decaying to WZ→ℓνℓ′ℓ′ (ℓ, ℓ′=e, μ) final states. The data were recorded by the ATLAS detector in s√=7  TeV pp collisions at the Large Hadron Collider and correspond to an integrated luminosity of 1.02  fb−1. The transverse mass distribution of the selected WZ candidates is found to be consistent with the standard model expectation. Upper limits on the production cross section times branching ratio are derived using two benchmark models predicting a heavy particle decaying to a WZ pair.