Erro : javax.persistence.PersistenceException: could not insert:

Pessoal, estou fazendo a rotina abaixo e esta dando erro abaixo:

[code]
Hibernate:
insert
into
cliente
(idade, nome)
values
(?, ?)
Exception in thread “main” javax.persistence.PersistenceException: org.hibernate.exception.SQLGrammarException: could not insert: [br.com.exemplo.entidade.Cliente]
at org.hibernate.ejb.AbstractEntityManagerImpl.throwPersistenceException(AbstractEntityManagerImpl.java:630)
at org.hibernate.ejb.AbstractEntityManagerImpl.merge(AbstractEntityManagerImpl.java:237)
at br.com.exemplo.repositorio.RepositorioCliente.Salvar(RepositorioCliente.java:24)
at br.com.exemplo.testes.testes.main(testes.java:12)
Caused by: org.hibernate.exception.SQLGrammarException: could not insert: [br.com.exemplo.entidade.Cliente]
at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:67)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43)
at org.hibernate.id.insert.AbstractReturningDelegate.performInsert(AbstractReturningDelegate.java:40)
at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2158)
at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2638)
at org.hibernate.action.EntityIdentityInsertAction.execute(EntityIdentityInsertAction.java:48)
at org.hibernate.engine.ActionQueue.execute(ActionQueue.java:250)
at org.hibernate.event.def.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:298)
at org.hibernate.event.def.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:181)
at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:107)
at org.hibernate.ejb.event.EJB3MergeEventListener.saveWithGeneratedId(EJB3MergeEventListener.java:43)
at org.hibernate.event.def.DefaultMergeEventListener.entityIsTransient(DefaultMergeEventListener.java:186)
at org.hibernate.event.def.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:123)
at org.hibernate.event.def.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:53)
at org.hibernate.impl.SessionImpl.fireMerge(SessionImpl.java:677)
at org.hibernate.impl.SessionImpl.merge(SessionImpl.java:661)
at org.hibernate.impl.SessionImpl.merge(SessionImpl.java:665)
at org.hibernate.ejb.AbstractEntityManagerImpl.merge(AbstractEntityManagerImpl.java:228)
… 2 more
Caused by: org.postgresql.util.PSQLException: ERRO: relação “cliente” não existe
Posição: 13
at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:2102)
at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:1835)
at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:257)
at org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:500)
at org.postgresql.jdbc2.AbstractJdbc2Statement.executeWithFlags(AbstractJdbc2Statement.java:388)
at org.postgresql.jdbc2.AbstractJdbc2Statement.executeUpdate(AbstractJdbc2Statement.java:334)
at org.hibernate.id.IdentityGenerator$GetGeneratedKeysDelegate.executeAndExtract(IdentityGenerator.java:73)
at org.hibernate.id.insert.AbstractReturningDelegate.performInsert(AbstractReturningDelegate.java:33)
… 17 more

[code]


<?xml version="1.0" encoding="UTF-8"?>
<persistence version="1.0"
	xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd">
    <persistence-unit name="mohr" transaction-type="RESOURCE_LOCAL">  
    	<provider>org.hibernate.ejb.HibernatePersistence</provider>

        <class>br.com.exemplo.entidade.Cliente</class> 
    	  
        <properties>
       		
       		
      		 
            <!-- Conexão com o banco de dados -->
			<property name="hibernate.dialect" value="org.hibernate.dialect.PostgreSQLDialect" />
			<property name="hibernate.connection.driver_class" value="org.postgresql.Driver" />
			<property name="hibernate.connection.url" value="jdbc:postgresql://localhost:5432/postgres" />
			<property name="hibernate.connection.user" value="postgres" />
			<property name="hibernate.connection.password" value="xavier" />
<!--             <property name="hibernate.hbm2ddl.auto" value="create" /> -->
            <property name="hibernate.hbm2ddl.auto" value="update"/>
 
            <!--Configuracoes de Debug-->
			<property name="hibernate.show_sql" value="true" />
			<property name="hibernate.format_sql" value="true" />
			<property name="use_sql_comments" value="true" />
			
		</properties>
    </persistence-unit>
</persistence>


@Entity
@Table(name="cliente")
public class Cliente {
	@Id
	@GeneratedValue(strategy = GenerationType.IDENTITY)
	private int id;
	@Column
	private String nome;
	@Column
	private int idade;
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public String getNome() {
		return nome;
	}
	public void setNome(String nome) {
		this.nome = nome;
	}
	public int getIdade() {
		return idade;
	}
	public void setIdade(int idade) {
		this.idade = idade;
	}

}

public class testes {
	public static void main(String[] args) {
		RepositorioCliente repositorioCliente = new RepositorioCliente();
		Cliente cliente = new Cliente();
		cliente.setNome("Fulano");
		cliente.setIdade(15);
		repositorioCliente.Salvar(cliente);
	}

}

public class RepositorioCliente {
	EntityManagerFactory emf;
	EntityManager em;
	
	
	public RepositorioCliente() {
		emf = Persistence.createEntityManagerFactory("mohr");
		em = emf.createEntityManager();
	}
	
	public void Salvar(Cliente cliente) {
		em.getTransaction().begin();
		em.merge(cliente);
		em.getTransaction().commit();
		emf.close();
	}
	
	public void Remover(Cliente cliente){
		em.getTransaction().begin();
		em.remove(cliente);
		em.getTransaction().commit();
		emf.close();
		
	}
	
	@SuppressWarnings("unchecked")
	public List<Cliente> listartodos() {
		em.getTransaction().begin();		
		Query consulta = em.createQuery("select c from Cliente c");
		List<Cliente> clientes = consulta.getResultList();
		em.getTransaction().commit();
		emf.close();
				
		return clientes;
		
	}

}


Aparentemente não existe a tabela cliente na tua base de dados.